diff --git a/source/tanya/container/buffer.d b/source/tanya/container/buffer.d
index 3d7205b..999cff5 100644
--- a/source/tanya/container/buffer.d
+++ b/source/tanya/container/buffer.d
@@ -12,8 +12,6 @@ module tanya.container.buffer;
 
 import tanya.memory;
 
-@nogc:
-
 version (unittest)
 {
 	private int fillBuffer(void* buffer,
@@ -42,7 +40,6 @@ version (unittest)
  */
 interface Buffer
 {
-@nogc:
 	/**
 	 * Returns: The size of the internal buffer.
 	 */
@@ -74,7 +71,6 @@ interface Buffer
  */
 class ReadBuffer : Buffer
 {
-@nogc:
 	/// Internal buffer.
 	protected ubyte[] _buffer;
 
@@ -87,7 +83,7 @@ class ReadBuffer : Buffer
 	/// Size by which the buffer will grow.
 	protected immutable size_t blockSize;
 
-	private Allocator allocator;
+	private shared Allocator allocator;
 
 	invariant
 	{
@@ -107,7 +103,7 @@ class ReadBuffer : Buffer
 	 */
 	this(size_t size = 8192,
 	     size_t minAvailable = 1024,
-	     Allocator allocator = defaultAllocator)
+	     shared Allocator allocator = defaultAllocator)
 	{
 		this.allocator = allocator;
 		this.minAvailable = minAvailable;
@@ -294,7 +290,6 @@ class ReadBuffer : Buffer
  */
 class WriteBuffer : Buffer
 {
-@nogc:
 	/// Internal buffer.
 	protected ubyte[] _buffer;
 
@@ -310,7 +305,7 @@ class WriteBuffer : Buffer
 	/// The position of the free area in the buffer.
 	protected size_t position;
 
-	private Allocator allocator;
+	private shared Allocator allocator;
 
 	invariant
 	{
@@ -325,7 +320,7 @@ class WriteBuffer : Buffer
 	 * 	       will grow.
 	 */
 	this(size_t size = 8192,
-	     Allocator allocator = defaultAllocator)
+	     shared Allocator allocator = defaultAllocator)
 	{
 		this.allocator = allocator;
 		blockSize = size;
diff --git a/source/tanya/container/list.d b/source/tanya/container/list.d
index e6e4ffc..e3bf25c 100644
--- a/source/tanya/container/list.d
+++ b/source/tanya/container/list.d
@@ -20,7 +20,6 @@ import tanya.memory;
  */
 class SList(T)
 {
-@nogc:
 	/**
 	 * Creates a new $(D_PSYMBOL SList).
 	 *
@@ -28,7 +27,7 @@ class SList(T)
 	 * 	allocator = The allocator should be used for the element
 	 * 	            allocations.
 	 */
-	this(Allocator allocator = defaultAllocator)
+	this(shared Allocator allocator = defaultAllocator)
 	{
 		this.allocator = allocator;
         reset();
@@ -241,7 +240,7 @@ class SList(T)
 	 * Params:
 	 * 	dg = $(D_KEYWORD foreach) body.
 	 */
-	int opApply(int delegate(ref size_t i, ref T) @nogc dg)
+	int opApply(int delegate(ref size_t i, ref T) dg)
 	{
 		int result;
 		size_t i;
@@ -280,7 +279,7 @@ class SList(T)
 	}
 
 	/// Ditto.
-	int opApply(int delegate(ref T) @nogc dg)
+	int opApply(int delegate(ref T) dg)
 	{
 		int result;
 
@@ -389,7 +388,7 @@ class SList(T)
 	/// Current position in the list.
 	protected Entry* position;
 
-	private Allocator allocator;
+	private shared Allocator allocator;
 }
 
 interface Stuff
diff --git a/source/tanya/container/queue.d b/source/tanya/container/queue.d
index 0890bcf..de28de2 100644
--- a/source/tanya/container/queue.d
+++ b/source/tanya/container/queue.d
@@ -20,7 +20,6 @@ import tanya.memory;
  */
 class Queue(T)
 {
-@nogc:
 	/**
 	 * Creates a new $(D_PSYMBOL Queue).
 	 *
@@ -28,7 +27,7 @@ class Queue(T)
 	 * 	allocator = The allocator should be used for the element
 	 * 	            allocations.
 	 */
-	this(Allocator allocator = defaultAllocator)
+	this(shared Allocator allocator = defaultAllocator)
 	{
 		this.allocator = allocator;
 	}
@@ -207,7 +206,7 @@ class Queue(T)
 	/// The last element of the list.
 	protected Entry* rear;
 
-	private Allocator allocator;
+	private shared Allocator allocator;
 }
 
 ///
diff --git a/source/tanya/container/vector.d b/source/tanya/container/vector.d
index 4f66dda..fb8353b 100644
--- a/source/tanya/container/vector.d
+++ b/source/tanya/container/vector.d
@@ -12,8 +12,6 @@ module tanya.container.vector;
 
 import tanya.memory;
 
-@nogc:
-
 /**
  * One dimensional array. It allocates automatically if needed.
  *
@@ -34,7 +32,6 @@ import tanya.memory;
  */
 class Vector(T)
 {
-@nogc:
 	/**
 	 * Creates a new $(D_PSYMBOL Vector).
 	 *
@@ -43,14 +40,14 @@ class Vector(T)
 	 * 	allocator = The allocator should be used for the element
 	 * 	            allocations.
 	 */
-	this(size_t length, Allocator allocator = defaultAllocator)
+	this(size_t length, shared Allocator allocator = defaultAllocator)
 	{
 		this.allocator = allocator;
 		vector = makeArray!T(allocator, length);
 	}
 
 	/// Ditto.
-	this(Allocator allocator = defaultAllocator)
+	this(shared Allocator allocator = defaultAllocator)
 	{
 		this(0, allocator);
 	}
@@ -194,7 +191,7 @@ class Vector(T)
 	 * Params:
 	 * 	dg = $(D_KEYWORD foreach) body.
 	 */
-	int opApply(int delegate(ref T) @nogc dg)
+	int opApply(int delegate(ref T) dg)
 	{
 		int result;
 
@@ -211,7 +208,7 @@ class Vector(T)
 	}
 
 	/// Ditto.
-	int opApply(int delegate(ref size_t i, ref T) @nogc dg)
+	int opApply(int delegate(ref size_t i, ref T) dg)
 	{
 		int result;
 
@@ -408,7 +405,7 @@ class Vector(T)
 	/// Container.
 	protected T[] vector;
 
-	private Allocator allocator;
+	private shared Allocator allocator;
 }
 
 ///
diff --git a/source/tanya/crypto/cipher.d b/source/tanya/crypto/cipher.d
index 60d1587..d436feb 100644
--- a/source/tanya/crypto/cipher.d
+++ b/source/tanya/crypto/cipher.d
@@ -43,7 +43,7 @@ enum Mode
 ubyte[] applyPadding(ref ubyte[] input,
                      in Mode mode,
                      in ushort blockSize,
-                     Allocator allocator = defaultAllocator)
+                     shared Allocator allocator = defaultAllocator)
 in
 {
 	assert(blockSize > 0 && blockSize <= 256);
@@ -204,7 +204,7 @@ unittest
 ref ubyte[] removePadding(ref ubyte[] input,
                       in Mode mode,
                       in ushort blockSize,
-                      Allocator allocator = defaultAllocator)
+                      shared Allocator allocator = defaultAllocator)
 in
 {
 	assert(input.length != 0);
diff --git a/source/tanya/event/internal/epoll.d b/source/tanya/event/internal/epoll.d
index f4e99d9..0e76c3a 100644
--- a/source/tanya/event/internal/epoll.d
+++ b/source/tanya/event/internal/epoll.d
@@ -28,8 +28,6 @@ import core.sys.posix.netinet.in_;
 import core.time;
 import std.algorithm.comparison;
 
-@nogc:
-
 extern (C) nothrow
 { // TODO: Make a pull request for Phobos to mark this extern functions as @nogc.
     int epoll_create1(int __flags);
@@ -42,7 +40,6 @@ private enum maxEvents = 128;
 
 class EpollLoop : Loop
 {
-@nogc:
 	/**
 	 * Initializes the loop.
 	 */
@@ -108,7 +105,7 @@ class EpollLoop : Loop
 	 * 	protocolFactory = Protocol factory.
 	 * 	socket          = Socket.
 	 */
-	protected override void acceptConnection(Protocol delegate() @nogc protocolFactory,
+	protected override void acceptConnection(Protocol delegate() protocolFactory,
 	                                         int socket)
 	{
 		sockaddr_in client_addr;
diff --git a/source/tanya/event/internal/selector.d b/source/tanya/event/internal/selector.d
index 9682a5d..36dca76 100644
--- a/source/tanya/event/internal/selector.d
+++ b/source/tanya/event/internal/selector.d
@@ -24,7 +24,6 @@ import core.sys.posix.unistd;
  */
 class SocketTransport : DuplexTransport
 {
-@nogc:
 	private int socket_ = -1;
 
 	private Protocol protocol_;
diff --git a/source/tanya/event/loop.d b/source/tanya/event/loop.d
index 4383845..73b0557 100644
--- a/source/tanya/event/loop.d
+++ b/source/tanya/event/loop.d
@@ -29,8 +29,6 @@ static if (UseEpoll)
     import tanya.event.internal.epoll;
 }
 
-@nogc:
-
 /**
  * Events.
  */
@@ -49,7 +47,6 @@ alias EventMask = BitFlags!Event;
  */
 abstract class Loop
 {
-@nogc:
 	/// Pending watchers.
 	protected Queue!Watcher pendings;
 
@@ -204,7 +201,7 @@ abstract class Loop
 	 * 	protocolFactory = Protocol factory.
 	 * 	socket          = Socket.
 	 */
-	protected void acceptConnection(Protocol delegate() @nogc protocolFactory,
+	protected void acceptConnection(Protocol delegate() protocolFactory,
 	                                int socket);
 
 	/// Whether the event loop should be stopped.
@@ -219,7 +216,6 @@ abstract class Loop
  */
 class BadLoopException : Exception
 {
-@nogc:
 	/**
 	 * Params:
 	 * 	file = The file where the exception occurred.
@@ -227,7 +223,7 @@ class BadLoopException : Exception
 	 * 	next = The previous exception in the chain of exceptions, if any.
 	 */
 	this(string file = __FILE__, size_t line = __LINE__, Throwable next = null)
-	pure @safe nothrow const
+	pure @safe nothrow const @nogc
 	{
 		super("Event loop cannot be initialized.", file, line, next);
 	}
diff --git a/source/tanya/event/transport.d b/source/tanya/event/transport.d
index 7a3a60a..e1dc6f7 100644
--- a/source/tanya/event/transport.d
+++ b/source/tanya/event/transport.d
@@ -18,7 +18,6 @@ import tanya.event.protocol;
  */
 class TransportException : Exception
 {
-@nogc:
 	/**
 	 * Params:
 	 * 	msg  = Message to output.
@@ -29,7 +28,7 @@ class TransportException : Exception
 	this(string msg,
 	     string file = __FILE__,
 	     size_t line = __LINE__,
-	     Throwable next = null) pure @safe nothrow const
+	     Throwable next = null) pure @safe nothrow const @nogc
 	{
 		super(msg, file, line, next);
 	}
@@ -40,7 +39,6 @@ class TransportException : Exception
  */
 interface Transport
 {
-@nogc:
 	/**
 	 * Returns: Protocol.
 	 */
@@ -78,7 +76,6 @@ interface Transport
  */
 interface ReadTransport : Transport
 {
-@nogc:
 	/**
 	 * Returns: Underlying output buffer.
 	 */
@@ -103,7 +100,6 @@ interface ReadTransport : Transport
  */
 interface WriteTransport : Transport
 {
-@nogc:
 	/**
 	 * Returns: Underlying input buffer.
 	 */
diff --git a/source/tanya/event/watcher.d b/source/tanya/event/watcher.d
index f0ed9e1..e19a21b 100644
--- a/source/tanya/event/watcher.d
+++ b/source/tanya/event/watcher.d
@@ -21,7 +21,6 @@ import std.functional;
  */
 abstract class Watcher
 {
-@nogc:
     /// Whether the watcher is active.
     bool active;
 
@@ -33,7 +32,6 @@ abstract class Watcher
 
 class ConnectionWatcher : Watcher
 {
-@nogc:
 	/// Watched file descriptor.
     private int socket_;
 
@@ -41,7 +39,7 @@ class ConnectionWatcher : Watcher
 	protected Protocol delegate() protocolFactory;
 
 	/// Callback.
-	package void delegate(Protocol delegate() @nogc protocolFactory,
+	package void delegate(Protocol delegate() protocolFactory,
 	                      int socket) accept;
 
 	invariant
@@ -54,27 +52,27 @@ class ConnectionWatcher : Watcher
 	 * 	protocolFactory = Function returning a new $(D_PSYMBOL Protocol) instance.
 	 * 	socket          = Socket.
 	 */
-	this(Protocol function() @nogc protocolFactory, int socket)
+	this(Protocol function() protocolFactory, int socket)
 	{
 		this.protocolFactory = toDelegate(protocolFactory);
 		socket_ = socket;
 	}
 
 	/// Ditto.
-	this(Protocol delegate() @nogc protocolFactory, int socket)
+	this(Protocol delegate() protocolFactory, int socket)
 	{
 		this.protocolFactory = protocolFactory;
 		socket_ = socket;
 	}
 
 	/// Ditto.
-	protected this(Protocol function() @nogc protocolFactory)
+	protected this(Protocol function() protocolFactory)
 	{
 		this.protocolFactory = toDelegate(protocolFactory);
 	}
 
 	/// Ditto.
-	protected this(Protocol delegate() @nogc protocolFactory)
+	protected this(Protocol delegate() protocolFactory)
 	{
 		this.protocolFactory = protocolFactory;
 	}
@@ -90,7 +88,7 @@ class ConnectionWatcher : Watcher
 	/**
 	 * Returns: Application protocol factory.
 	 */
-	@property inout(Protocol delegate() @nogc) protocol() inout
+	@property inout(Protocol delegate()) protocol() inout
 	{
 		return protocolFactory;
 	}
@@ -107,7 +105,6 @@ class ConnectionWatcher : Watcher
  */
 class IOWatcher : ConnectionWatcher
 {
-@nogc:
 	/// References a watcher or a transport.
 	DuplexTransport transport_;
 
@@ -116,7 +113,7 @@ class IOWatcher : ConnectionWatcher
 	 * 	protocolFactory = Function returning application specific protocol.
 	 * 	transport       = Transport.
 	 */
-	this(Protocol delegate() @nogc protocolFactory,
+	this(Protocol delegate() protocolFactory,
 		 DuplexTransport transport)
 	in
 	{
@@ -143,7 +140,7 @@ class IOWatcher : ConnectionWatcher
      *
 	 * Returns: $(D_KEYWORD this).
      */
-	IOWatcher opCall(Protocol delegate() @nogc protocolFactory,
+	IOWatcher opCall(Protocol delegate() protocolFactory,
 	                 DuplexTransport transport) @safe pure nothrow
 	in
 	{
diff --git a/source/tanya/memory/allocator.d b/source/tanya/memory/allocator.d
index c206826..07a19b9 100644
--- a/source/tanya/memory/allocator.d
+++ b/source/tanya/memory/allocator.d
@@ -10,49 +10,75 @@
  */  
 module tanya.memory.allocator;
 
+import std.experimental.allocator;
+import std.traits;
+
 /**
- * This interface should be similar to $(D_PSYMBOL
- * std.experimental.allocator.IAllocator), but usable in
- * $(D_KEYWORD @nogc)-code.
+ * Allocator interface.
  */
 interface Allocator
 {
-@nogc:
-	/**
-	 * Allocates $(D_PARAM s) bytes of memory.
-	 *
-	 * Params:
-	 * 	s = Amount of memory to allocate.
-	 *
-	 * Returns: The pointer to the new allocated memory.
-	 */
-    void[] allocate(size_t s) @safe;
+    /**
+     * Allocates $(D_PARAM size) bytes of memory.
+     *
+     * Params:
+     *     size = Amount of memory to allocate.
+     *
+     * Returns: The pointer to the new allocated memory.
+     */
+    void[] allocate(size_t size) shared;
 
     /**
-	 * Deallocates a memory block.
-	 *
-	 * Params:
-	 * 	p = A pointer to the memory block to be freed.
-	 *
-	 * Returns: Whether the deallocation was successful.
-	 */
-    bool deallocate(void[] p) @safe;
+     * Deallocates a memory block.
+     *
+     * Params:
+     *     p = A pointer to the memory block to be freed.
+     *
+     * Returns: Whether the deallocation was successful.
+     */
+    bool deallocate(void[] p) shared;
 
-	/**
-	 * Increases or decreases the size of a memory block.
-	 *
-	 * Params:
-	 * 	p    = A pointer to the memory block.
-	 * 	size = Size of the reallocated block.
-	 *
-	 * Returns: Whether the reallocation was successful.
-	 */
-	bool reallocate(ref void[] p, size_t s) @safe;
+    /**
+     * Increases or decreases the size of a memory block.
+     *
+     * Params:
+     *     p    = A pointer to the memory block.
+     *     size = Size of the reallocated block.
+     *
+     * Returns: Whether the reallocation was successful.
+     */
+    bool reallocate(ref void[] p, size_t size) shared;
 
-	/**
-     * Static allocator instance and initializer.
-	 *
-	 * Returns: An $(D_PSYMBOL Allocator) instance.
-	 */
-	static @property Allocator instance() @safe;
+    /**
+     * Returns: The alignment offered.
+     */
+    @property immutable(uint) alignment() shared const @safe pure nothrow;
 }
+
+/**
+ * Params:
+ *     T         = Element type of the array being created.
+ *     allocator = The allocator used for getting memory.
+ *     array     = A reference to the array being changed.
+ *     length    = New array length.
+ *
+ * Returns: $(D_KEYWORD true) upon success, $(D_KEYWORD false) if memory could
+ *          not be reallocated. In the latter
+ */
+bool resizeArray(T)(shared Allocator allocator,
+                    ref T[] array,
+                    in size_t length)
+{
+    void[] buf = array;
+
+    if (!allocator.reallocate(buf, length * T.sizeof))
+    {
+        return false;
+    }
+    array = cast(T[]) buf;
+
+    return true;
+}
+
+enum bool isFinalizable(T) = is(T == class) || is(T == interface)
+                           || hasElaborateDestructor!T || isDynamicArray!T;
diff --git a/source/tanya/memory/package.d b/source/tanya/memory/package.d
index 67114df..4157fb2 100644
--- a/source/tanya/memory/package.d
+++ b/source/tanya/memory/package.d
@@ -26,8 +26,6 @@ else version (Posix)
 	import core.sys.posix.pthread;
 }
 
-@nogc:
-
 version (Windows)
 {
 	package alias Mutex = CRITICAL_SECTION;
@@ -42,12 +40,12 @@ else version (Posix)
 	}
 }
 
-@property void defaultAllocator(Allocator allocator) @safe nothrow
+@property void defaultAllocator(shared Allocator allocator) @safe nothrow
 {
 	_defaultAllocator = allocator;
 }
 
-@property Allocator defaultAllocator() @safe nothrow
+@property shared(Allocator) defaultAllocator() @safe nothrow
 {
 	return _defaultAllocator;
 }
@@ -204,4 +202,4 @@ bool resizeArray(T, A)(auto ref A allocator, ref T[] array, in size_t length)
 enum bool isFinalizable(T) = is(T == class) || is(T == interface)
                           || hasElaborateDestructor!T || isDynamicArray!T;
 
-private Allocator _defaultAllocator;
+private shared Allocator _defaultAllocator;
diff --git a/source/tanya/memory/ullocator.d b/source/tanya/memory/ullocator.d
index 54af6b4..43761f7 100644
--- a/source/tanya/memory/ullocator.d
+++ b/source/tanya/memory/ullocator.d
@@ -7,28 +7,33 @@
  * License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
  *                  Mozilla Public License, v. 2.0).
  * Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
- */  
+ */
 module tanya.memory.ullocator;
 
 import tanya.memory.allocator;
+import core.atomic;
+import core.exception;
 
-@nogc:
-
-version (Posix):
-
-import core.sys.posix.sys.mman;
-import core.sys.posix.unistd;
+version (Posix)
+{
+    import core.stdc.errno;
+    import core.sys.posix.sys.mman;
+    import core.sys.posix.unistd;
+}
+else version (Windows)
+{
+    import core.sys.windows.winbase;
+    import core.sys.windows.windows;
+}
 
 /**
- * Allocator for Posix systems with mmap/munmap support.
- *
  * This allocator allocates memory in regions (multiple of 4 KB for example).
  * Each region is then splitted in blocks. So it doesn't request the memory
  * from the operating system on each call, but only if there are no large
- * enought free blocks in the available regions.
+ * enough free blocks in the available regions.
  * Deallocation works in the same way. Deallocation doesn't immediately
  * gives the memory back to the operating system, but marks the appropriate
- * block as free and only if all blocks in the region are free, the complet
+ * block as free and only if all blocks in the region are free, the complete
  * region is deallocated.
  *
  * ----------------------------------------------------------------------------
@@ -42,382 +47,440 @@ import core.sys.posix.unistd;
  * |  N   |    -----------> next|            ||   N  |     |                  |
  * |      |     |         |     |            ||      |     |                  |
  * --------------------------------------------------- ------------------------
+ *
+ * TODO:
+ *     $(UL
+ *         $(LI Thread safety (core.atomic.cas))
+ *         $(LI If two neighbour blocks are free, they can be merged)
+ *         $(LI Reallocation shoud check if there is enough free space in the
+ *              next block instead of always moving the memory)
+ *         $(LI Make 64 KB regions mininmal region size on Linux)
+ *     )
  */
 class Ullocator : Allocator
 {
-@nogc:
-	@disable this();
+    @disable this();
 
-	shared static this() @safe nothrow
-	{
-		pageSize = sysconf(_SC_PAGE_SIZE);
-	}
-
-	/**
-	 * Allocates $(D_PARAM size) bytes of memory.
-	 *
-	 * Params:
-	 * 	size = Amount of memory to allocate.
-	 *
-	 * Returns: The pointer to the new allocated memory.
-	 */
-    void[] allocate(size_t size) @trusted nothrow
+    shared static this()
     {
-		immutable dataSize = addAlignment(size);
-
-		void* data = findBlock(dataSize);
-		if (data is null)
-		{
-			data = initializeRegion(dataSize);
-		}
-
-		return data is null ? null : data[0..size];
+        version (Posix)
+        {
+            pageSize = sysconf(_SC_PAGE_SIZE);
+        }
+        else version (Windows)
+        {
+            SYSTEM_INFO si;
+            GetSystemInfo(&si);
+            pageSize = si.dwPageSize;
+        }
     }
 
-	///
-	unittest
-	{
-		auto p = Ullocator.instance.allocate(20);
-
-		assert(p);
-
-		Ullocator.instance.deallocate(p);
-	}
-
-	/**
-	 * Search for a block large enough to keep $(D_PARAM size) and split it
-	 * into two blocks if the block is too large.
-	 *
-	 * Params:
-	 * 	size = Minimum size the block should have.
-	 *
-	 * Returns: Data the block points to or $(D_KEYWORD null).
-	 */
-	private void* findBlock(size_t size) nothrow
-	{
-		Block block1;
-		RegionLoop: for (auto r = head; r !is null; r = r.next)
-		{
-			block1 = cast(Block) (cast(void*) r + regionEntrySize);
-			do
-			{
-				if (block1.free && block1.size >= size)
-				{
-					break RegionLoop;
-				}
-			}
-			while ((block1 = block1.next) !is null);
-		}
-		if (block1 is null)
-		{
-			return null;
-		}
-		else if (block1.size >= size + alignment + blockEntrySize)
-		{ // Split the block if needed
-			Block block2 = cast(Block) (cast(void*) block1 + blockEntrySize + size);
-			block2.prev = block1;
-			if (block1.next is null)
-			{
-				block2.next = null;
-			}
-			else
-			{
-				block2.next = block1.next.next;
-			}
-			block1.next = block2;
-
-			block1.free = false;
-			block2.free = true;
-
-			block2.size = block1.size - blockEntrySize - size;
-			block1.size = size;
-
-			block2.region = block1.region;
-			++block1.region.blocks;
-		}
-		else
-		{
-			block1.free = false;
-			++block1.region.blocks;
-		}
-		return cast(void*) block1 + blockEntrySize;
-	}
-
     /**
-	 * Deallocates a memory block.
-	 *
-	 * Params:
-	 * 	p = A pointer to the memory block to be freed.
-	 *
-	 * Returns: Whether the deallocation was successful.
-	 */
-    bool deallocate(void[] p) @trusted nothrow
+     * Allocates $(D_PARAM size) bytes of memory.
+     *
+     * Params:
+     *     size = Amount of memory to allocate.
+     *
+     * Returns: The pointer to the new allocated memory.
+     */
+    void[] allocate(size_t size) shared @nogc @trusted nothrow
     {
-		if (p is null)
-		{
-			return true;
-		}
+        if (!size)
+        {
+            return null;
+        }
+        immutable dataSize = addAlignment(size);
 
-		Block block = cast(Block) (p.ptr - blockEntrySize);
-		if (block.region.blocks <= 1)
-		{
-			if (block.region.prev !is null)
-			{
-				block.region.prev.next = block.region.next;
-			}
-			else // Replace the list head. It is being deallocated
-			{
-				head = block.region.next;
-			}
-			if (block.region.next !is null)
-			{
-				block.region.next.prev = block.region.prev;
-			}
-			return munmap(block.region, block.region.size) == 0;
-		}
-		else
-		{
-			block.free = true;
-			--block.region.blocks;
-			return true;
-		}
+        void* data = findBlock(dataSize);
+        if (data is null)
+        {
+            data = initializeRegion(dataSize);
+        }
+
+        return data is null ? null : data[0..size];
     }
 
-	///
-	unittest
-	{
-		auto p = Ullocator.instance.allocate(20);
+    ///
+    @nogc @safe nothrow unittest
+    {
+        auto p = Ullocator.instance.allocate(20);
 
-		assert(Ullocator.instance.deallocate(p));
-	}
+        assert(p);
 
-	/**
-	 * Increases or decreases the size of a memory block.
-	 *
-	 * Params:
-	 * 	p    = A pointer to the memory block.
-	 * 	size = Size of the reallocated block.
-	 *
-	 * Returns: Whether the reallocation was successful.
-	 */
-	bool reallocate(ref void[] p, size_t size) @trusted nothrow
-	{
-		if (size == p.length)
-		{
-			return true;
-		}
+        Ullocator.instance.deallocate(p);
+    }
 
-		auto reallocP = allocate(size);
-		if (reallocP is null)
-		{
-			return false;
-		}
+    /**
+     * Search for a block large enough to keep $(D_PARAM size) and split it
+     * into two blocks if the block is too large.
+     *
+     * Params:
+     *     size = Minimum size the block should have.
+     *
+     * Returns: Data the block points to or $(D_KEYWORD null).
+     */
+    private void* findBlock(size_t size) shared @nogc nothrow
+    {
+        Block block1;
+        RegionLoop: for (auto r = head; r !is null; r = r.next)
+        {
+            block1 = cast(Block) (cast(void*) r + regionEntrySize);
+            do
+            {
+                if (block1.free && block1.size >= size)
+                {
+                    break RegionLoop;
+                }
+            }
+            while ((block1 = block1.next) !is null);
+        }
+        if (block1 is null)
+        {
+            return null;
+        }
+        else if (block1.size >= size + alignment + blockEntrySize)
+        { // Split the block if needed
+            Block block2 = cast(Block) (cast(void*) block1 + blockEntrySize + size);
+            block2.prev = block1;
+            if (block1.next is null)
+            {
+                block2.next = null;
+            }
+            else
+            {
+                block2.next = block1.next.next;
+            }
+            block1.next = block2;
 
-		if (p !is null)
-		{
-			if (size > p.length)
-			{
-				reallocP[0..p.length] = p[0..$];
-			}
-			else
-			{
-				reallocP[0..size] = p[0..size];
-			}
-			deallocate(p);
-		}
-		p = reallocP;
+            block1.free = false;
+            block2.free = true;
 
-		return true;
-	}
+            block2.size = block1.size - blockEntrySize - size;
+            block1.size = size;
 
-	///
-	unittest
-	{
-		void[] p;
-		Ullocator.instance.reallocate(p, 10 * int.sizeof);
-		(cast(int[]) p)[7] = 123;
+            block2.region = block1.region;
+            atomicOp!"+="(block1.region.blocks, 1);
+        }
+        else
+        {
+            block1.free = false;
+            atomicOp!"+="(block1.region.blocks, 1);
+        }
+        return cast(void*) block1 + blockEntrySize;
+    }
 
-		assert(p.length == 40);
+    /**
+     * Deallocates a memory block.
+     *
+     * Params:
+     *     p = A pointer to the memory block to be freed.
+     *
+     * Returns: Whether the deallocation was successful.
+     */
+    bool deallocate(void[] p) shared @nogc @trusted nothrow
+    {
+        if (p is null)
+        {
+            return true;
+        }
 
-		Ullocator.instance.reallocate(p, 8 * int.sizeof);
+        Block block = cast(Block) (p.ptr - blockEntrySize);
+        if (block.region.blocks <= 1)
+        {
+            if (block.region.prev !is null)
+            {
+                block.region.prev.next = block.region.next;
+            }
+            else // Replace the list head. It is being deallocated
+            {
+                head = block.region.next;
+            }
+            if (block.region.next !is null)
+            {
+                block.region.next.prev = block.region.prev;
+            }
+            version (Posix)
+            {
+                return munmap(cast(void*) block.region, block.region.size) == 0;
+            }
+            version (Windows)
+            {
+                return VirtualFree(cast(void*) block.region, 0, MEM_RELEASE) == 0;
+            }
+        }
+        else
+        {
+            block.free = true;
+            atomicOp!"-="(block.region.blocks, 1);
+            return true;
+        }
+    }
 
-		assert(p.length == 32);
-		assert((cast(int[]) p)[7] == 123);
+    ///
+    @nogc @safe nothrow unittest
+    {
+        auto p = Ullocator.instance.allocate(20);
 
-		Ullocator.instance.reallocate(p, 20 * int.sizeof);
-		(cast(int[]) p)[15] = 8;
+        assert(Ullocator.instance.deallocate(p));
+    }
 
-		assert(p.length == 80);
-		assert((cast(int[]) p)[15] == 8);
-		assert((cast(int[]) p)[7] == 123);
+    /**
+     * Increases or decreases the size of a memory block.
+     *
+     * Params:
+     *     p    = A pointer to the memory block.
+     *     size = Size of the reallocated block.
+     *
+     * Returns: Whether the reallocation was successful.
+     */
+    bool reallocate(ref void[] p, size_t size) shared @nogc @trusted nothrow
+    {
+        void[] reallocP;
 
-		Ullocator.instance.reallocate(p, 8 * int.sizeof);
+        if (size == p.length)
+        {
+            return true;
+        }
+        else if (size > 0)
+        {
+            reallocP = allocate(size);
+            if (reallocP is null)
+            {
+                return false;
+            }
+        }
 
-		assert(p.length == 32);
-		assert((cast(int[]) p)[7] == 123);
+        if (p !is null)
+        {
+            if (size > p.length)
+            {
+                reallocP[0..p.length] = p[0..$];
+            }
+            else if (size > 0)
+            {
+                reallocP[0..size] = p[0..size];
+            }
+            deallocate(p);
+        }
+        p = reallocP;
 
-		Ullocator.instance.deallocate(p);
-	}
+        return true;
+    }
 
-	/**
+    ///
+    @nogc @safe nothrow unittest
+    {
+        void[] p;
+        Ullocator.instance.reallocate(p, 10 * int.sizeof);
+        (cast(int[]) p)[7] = 123;
+
+        assert(p.length == 40);
+
+        Ullocator.instance.reallocate(p, 8 * int.sizeof);
+
+        assert(p.length == 32);
+        assert((cast(int[]) p)[7] == 123);
+
+        Ullocator.instance.reallocate(p, 20 * int.sizeof);
+        (cast(int[]) p)[15] = 8;
+
+        assert(p.length == 80);
+        assert((cast(int[]) p)[15] == 8);
+        assert((cast(int[]) p)[7] == 123);
+
+        Ullocator.instance.reallocate(p, 8 * int.sizeof);
+
+        assert(p.length == 32);
+        assert((cast(int[]) p)[7] == 123);
+
+        Ullocator.instance.deallocate(p);
+    }
+
+    /**
      * Static allocator instance and initializer.
-	 *
-	 * Returns: The global $(D_PSYMBOL Allocator) instance.
-	 */
-	static @property Ullocator instance() @trusted nothrow
-	{
-		if (instance_ is null)
-		{
-			immutable instanceSize = addAlignment(__traits(classInstanceSize, Ullocator));
+     *
+     * Returns: Global $(D_PSYMBOL Ullocator) instance.
+     */
+    static @property ref shared(Ullocator) instance() @nogc @trusted nothrow
+    {
+        if (instance_ is null)
+        {
+            immutable instanceSize = addAlignment(__traits(classInstanceSize, Ullocator));
 
-			Region head; // Will become soon our region list head
-			void* data = initializeRegion(instanceSize, head);
+            Region head; // Will become soon our region list head
+            void* data = initializeRegion(instanceSize, head);
+            if (data !is null)
+            {
+                data[0..instanceSize] = typeid(Ullocator).initializer[];
+                instance_ = cast(shared Ullocator) data;
+                instance_.head = head;
+            }
+        }
+        return instance_;
+    }
 
-			if (data is null)
-			{
-				return null;
-			}
-			data[0..instanceSize] = typeid(Ullocator).initializer[];
-			instance_ = cast(Ullocator) data;
-			instance_.head = head;
-		}
-		return instance_;
-	}
+    ///
+    @nogc @safe nothrow unittest
+    {
+        assert(instance is instance);
+    }
 
-	///
-	unittest
-	{
-		assert(instance is instance);
-	}
+    /**
+     * Initializes a region for one element.
+     *
+     * Params:
+     *     size = Aligned size of the first data block in the region.
+     *     head = Region list head.
+     *
+     * Returns: A pointer to the data.
+     */
+    pragma(inline)
+    private static void* initializeRegion(size_t size,
+                                          ref Region head) @nogc nothrow
+    {
+        immutable regionSize = calculateRegionSize(size);
+        
+        version (Posix)
+        {
+            void* p = mmap(null,
+                           regionSize,
+                           PROT_READ | PROT_WRITE,
+                           MAP_PRIVATE | MAP_ANON,
+                           -1,
+                           0);
+            if (p is MAP_FAILED)
+            {
+                if (errno == ENOMEM)
+                {
+                    onOutOfMemoryError();
+                }
+                return null;
+            }
+        }
+        else version (Windows)
+        {
+            void* p = VirtualAlloc(null,
+                                   regionSize,
+                                   MEM_COMMIT,
+                                   PAGE_READWRITE);
+            if (p is null)
+            {
+                if (GetLastError() == ERROR_NOT_ENOUGH_MEMORY)
+                {
+                    onOutOfMemoryError();
+                }
+                return null;
+            }
+        }
 
-	/**
-	 * Initializes a region for one element.
-	 *
-	 * Params:
-	 * 	size = Aligned size of the first data block in the region.
-	 *  head = Region list head.
-	 *
-	 * Returns: A pointer to the data.
-	 */
-	pragma(inline)
-	private static void* initializeRegion(size_t size,
-	                                      ref Region head) nothrow
-	{
-		immutable regionSize = calculateRegionSize(size);
-		void* p = mmap(null,
-		               regionSize,
-		               PROT_READ | PROT_WRITE,
-		               MAP_PRIVATE | MAP_ANON,
-		               -1,
-		               0);
-		if (p is MAP_FAILED)
-		{
-			return null;
-		}
+        Region region = cast(Region) p;
+        region.blocks = 1;
+        region.size = regionSize;
 
-		Region region = cast(Region) p;
-		region.blocks = 1;
-		region.size = regionSize;
+        // Set the pointer to the head of the region list
+        if (head !is null)
+        {
+            head.prev = region;
+        }
+        region.next = head;
+        region.prev = null;
+        head = region;
 
-		// Set the pointer to the head of the region list
-		if (head !is null)
-		{
-			head.prev = region;
-		}
-		region.next = head;
-		region.prev = null;
-		head = region;
+        // Initialize the data block
+        void* memoryPointer = p + regionEntrySize;
+        Block block1 = cast(Block) memoryPointer;
+        block1.size = size;
+        block1.free = false;
 
-		// Initialize the data block
-		void* memoryPointer = p + regionEntrySize;
-		Block block1 = cast(Block) memoryPointer;
-		block1.size = size;
-		block1.free = false;
+        // It is what we want to return
+        void* data = memoryPointer + blockEntrySize;
 
-		// It is what we want to return
-		void* data = memoryPointer + blockEntrySize;
+        // Free block after data
+        memoryPointer = data + size;
+        Block block2 = cast(Block) memoryPointer;
+        block1.prev = block2.next = null;
+        block1.next = block2;
+        block2.prev = block1;
+        block2.size = regionSize - size - regionEntrySize - blockEntrySize * 2;
+        block2.free = true;
+        block1.region = block2.region = region;
 
-		// Free block after data
-		memoryPointer = data + size;
-		Block block2 = cast(Block) memoryPointer;
-		block1.prev = block2.next = null;
-		block1.next = block2;
-		block2.prev = block1;
-		block2.size = regionSize - size - regionEntrySize - blockEntrySize * 2;
-		block2.free = true;
-		block1.region = block2.region = region;
+        return data;
+    }
 
-		return data;
-	}
+    /// Ditto.
+    private void* initializeRegion(size_t size) shared @nogc nothrow
+    {
+        return initializeRegion(size, head);
+    }
 
-	/// Ditto.
-	private void* initializeRegion(size_t size) nothrow
-	{
-		return initializeRegion(size, head);
-	}
+    /**
+     * Params:
+     *     x = Space to be aligned.
+     *
+     * Returns: Aligned size of $(D_PARAM x).
+     */
+    pragma(inline)
+    private static immutable(size_t) addAlignment(size_t x)
+    @nogc @safe pure nothrow
+    out (result)
+    {
+        assert(result > 0);
+    }
+    body
+    {
+        return (x - 1) / alignment_ * alignment_ + alignment_;
+    }
 
-	/**
-	 * Params:
-	 * 	x = Space to be aligned.
-	 *
-	 * Returns: Aligned size of $(D_PARAM x).
-	 */
-	pragma(inline)
-	private static immutable(size_t) addAlignment(size_t x) @safe pure nothrow
-	out (result)
-	{
-		assert(result > 0);
-	}
-	body
-	{
-		return (x - 1) / alignment * alignment + alignment;
-	}
+    /**
+     * Params:
+     *     x = Required space.
+     *
+     * Returns: Minimum region size (a multiple of $(D_PSYMBOL pageSize)).
+     */
+    pragma(inline)
+    private static immutable(size_t) calculateRegionSize(size_t x)
+    @nogc @safe pure nothrow
+    out (result)
+    {
+        assert(result > 0);
+    }
+    body
+    {
+        x += regionEntrySize + blockEntrySize * 2;
+        return x / pageSize * pageSize + pageSize;
+    }
 
-	/**
-	 * Params:
-	 * 	x = Required space.
-	 *
-	 * Returns: Minimum region size (a multiple of $(D_PSYMBOL pageSize)).
-	 */
-	pragma(inline)
-	private static immutable(size_t) calculateRegionSize(size_t x)
-	@safe pure nothrow
-	out (result)
-	{
-		assert(result > 0);
-	}
-	body
-	{
-		x += regionEntrySize + blockEntrySize * 2;
-		return x / pageSize * pageSize + pageSize;
-	}
+    @property immutable(uint) alignment() shared const @nogc @safe pure nothrow
+    {
+        return alignment_;
+    }
+    private enum alignment_ = 8;
 
-	enum alignment = 8;
+    private shared static Ullocator instance_;
 
-	private static Ullocator instance_;
+    private shared static immutable size_t pageSize;
 
-	private shared static immutable long pageSize;
+    private shared struct RegionEntry
+    {
+        Region prev;
+        Region next;
+        uint blocks;
+        size_t size;
+    }
+    private alias Region = shared RegionEntry*;
+    private enum regionEntrySize = 32;
 
-	private struct RegionEntry
-	{
-		Region prev;
-		Region next;
-		uint blocks;
-		ulong size;
-	}
-	private alias Region = RegionEntry*;
-	private enum regionEntrySize = 32;
+    private shared Region head;
 
-	private Region head;
-
-	private struct BlockEntry
-	{
-		Block prev;
-		Block next;
-		bool free;
-		ulong size;
-		Region region;
-	}
-	private alias Block = BlockEntry*;
-	private enum blockEntrySize = 40;
+    private shared struct BlockEntry
+    {
+        Block prev;
+        Block next;
+        bool free;
+        size_t size;
+        Region region;
+    }
+    private alias Block = shared BlockEntry*;
+    private enum blockEntrySize = 40;
 }
diff --git a/source/tanya/random.d b/source/tanya/random.d
index bf749c7..4e9197d 100644
--- a/source/tanya/random.d
+++ b/source/tanya/random.d
@@ -14,8 +14,6 @@ import tanya.memory;
 import std.digest.sha;
 import std.typecons;
 
-@nogc:
-
 /// Block size of entropy accumulator (SHA-512).
 enum blockSize = 64;
 
@@ -27,7 +25,6 @@ enum maxGather = 128;
  */
 class EntropyException : Exception
 {
-@nogc:
 	/**
 	 * Params:
 	 * 	msg  = Message to output.
@@ -38,7 +35,7 @@ class EntropyException : Exception
 	this(string msg,
 	     string file = __FILE__,
 	     size_t line = __LINE__,
-	     Throwable next = null) pure @safe nothrow const
+	     Throwable next = null) pure @safe nothrow const @nogc
 	{
 		super(msg, file, line, next);
 	}
@@ -49,7 +46,6 @@ class EntropyException : Exception
  */
 abstract class EntropySource
 {
-@nogc:
 	/// Amount of already generated entropy.
 	protected ushort size_;
 
@@ -103,7 +99,6 @@ version (linux)
 	 */
 	class PlatformEntropySource : EntropySource
 	{
-	@nogc:
 		/**
 		 * Returns: Minimum bytes required from the entropy source.
 		 */
@@ -164,13 +159,12 @@ version (linux)
  */
 class Entropy
 {
-@nogc:
 	/// Entropy sources.
 	protected EntropySource[] sources;
 
 	private ubyte sourceCount_;
 
-	private Allocator allocator;
+	private shared Allocator allocator;
 
 	/// Entropy accumulator.
 	protected SHA!(maxGather * 8, 512) accumulator;
@@ -181,7 +175,7 @@ class Entropy
 	 * 	allocator  = Allocator to allocate entropy sources available on the
 	 * 	             system.
 	 */
-	this(size_t maxSources = 20, Allocator allocator = defaultAllocator)
+	this(size_t maxSources = 20, shared Allocator allocator = defaultAllocator)
 	in
 	{
 		assert(maxSources > 0 && maxSources <= ubyte.max);