diff --git a/backend/riscv.cpp b/backend/riscv.cpp
index 9bedb84..33ee410 100644
--- a/backend/riscv.cpp
+++ b/backend/riscv.cpp
@@ -157,6 +157,8 @@ namespace elna::riscv
 
     void visitor::prologue()
     {
+        this->variable_counter = 1;
+
         this->instructions.push_back(instruction(base_opcode::opImm));
         this->instructions.push_back(instruction(base_opcode::store));
         this->instructions.push_back(instruction(base_opcode::store));
@@ -195,7 +197,7 @@ namespace elna::riscv
         this->instructions.push_back(instruction(base_opcode::op)
             .r(x_register::a0, funct3_t::_and, x_register::zero, x_register::zero));
 
-        epilogue(static_cast<std::uint32_t>(variable_counter * 4 + 8 + main_symbol->stack_size()));
+        epilogue(static_cast<std::uint32_t>(this->variable_counter * 4 + 8 + main_symbol->stack_size()));
         this->writer->sink(definition->identifier(),
                 reinterpret_cast<const std::byte *>(this->instructions.data()),
                 this->instructions.size() * sizeof(instruction));
@@ -224,7 +226,7 @@ namespace elna::riscv
         this->instructions.push_back(instruction(base_opcode::op)
             .r(x_register::a0, funct3_t::_and, x_register::zero, x_register::zero));
 
-        epilogue(static_cast<std::uint32_t>(variable_counter * 4 + 8 + main_symbol->stack_size()));
+        epilogue(static_cast<std::uint32_t>(this->variable_counter * 4 + 8 + main_symbol->stack_size()));
         this->writer->sink("main", reinterpret_cast<const std::byte *>(this->instructions.data()),
                 this->instructions.size() * sizeof(instruction));
     }
diff --git a/cli/cl.cpp b/cli/cl.cpp
index d2799c0..61dfeed 100644
--- a/cli/cl.cpp
+++ b/cli/cl.cpp
@@ -38,7 +38,7 @@ namespace elna::cli
         {
             for (const auto& compile_error : lex_result.errors())
             {
-                std::cout << compile_error->line() << ':' << compile_error->column()
+                std::cerr << compile_error->line() << ':' << compile_error->column()
                     << ": " << compile_error->what() << std::endl;
             }
             return 1;
@@ -49,7 +49,7 @@ namespace elna::cli
         {
             for (const auto& compile_error : parser.errors())
             {
-                std::cout << compile_error->line() << ':' << compile_error->column()
+                std::cerr << compile_error->line() << ':' << compile_error->column()
                     << ": " << compile_error->what() << std::endl;
             }
             return 2;
diff --git a/include/elna/tester.hpp b/include/elna/tester.hpp
index e031ac6..a9b7fd1 100644
--- a/include/elna/tester.hpp
+++ b/include/elna/tester.hpp
@@ -44,8 +44,10 @@ namespace elna
         void add_exit_code(const test_status result) noexcept;
     };
 
-    test_result run_for_output(boost::asio::io_context& context, const std::filesystem::path& binary,
-            std::initializer_list<boost::string_view> arguments);
+    boost::process::v2::process_stdio get_output_streams(const std::uint8_t stream_number,
+            boost::asio::readable_pipe& read_pipe);
+    test_result run_for_output(boost::asio::io_context& context, const std::uint8_t stream_number,
+            const std::filesystem::path& binary, std::initializer_list<boost::string_view> arguments);
     test_result build_test(boost::asio::io_context& context, const std::filesystem::directory_entry& test_entry);
     test_result run_test(boost::asio::io_context& context, const std::filesystem::directory_entry& test_entry);
     void print_result(const std::filesystem::directory_entry& test_entry, const test_result& result);
diff --git a/source/parser.cpp b/source/parser.cpp
index 8db99c4..d47e4df 100644
--- a/source/parser.cpp
+++ b/source/parser.cpp
@@ -516,18 +516,43 @@ namespace elna::source
         }
         auto definition_identifier = iterator.advance(token::type::identifier);
 
-        if (!definition_identifier.has_value() || !iterator.skip(token::type::semicolon))
+        if (!definition_identifier.has_value() || !iterator.skip(token::type::left_paren))
         {
             return nullptr;
         }
+        std::vector<std::unique_ptr<declaration>> declarations;
+        while (!iterator.current(token::type::right_paren))
+        {
+            std::unique_ptr<declaration> parsed_declaration = parse_declaration();
+            if (parsed_declaration == nullptr)
+            {
+                return nullptr;
+            }
+            declarations.push_back(std::move(parsed_declaration));
+
+            if (iterator->of() == token::type::comma)
+            {
+                ++iterator;
+                continue;
+            }
+            else if (iterator->of() != token::type::right_paren)
+            {
+                iterator.add_error(*iterator);
+                return nullptr;
+            }
+        }
+        iterator.skip(token::type::right_paren);
         auto definition_body = parse_block();
 
         if (definition_body == nullptr || !iterator.skip(token::type::semicolon))
         {
             return nullptr;
         }
-        return std::make_unique<procedure_definition>(definition_identifier->get().identifier(),
+        auto procedure = std::make_unique<procedure_definition>(definition_identifier->get().identifier(),
                 std::move(definition_body));
+        procedure->parameters() = std::move(declarations);
+
+        return procedure;
     }
 
     std::unique_ptr<declaration> parser::parse_declaration()
diff --git a/tests/expectations/procedure_2_statements.txt b/tests/expectations/procedure_2_statements.txt
new file mode 100644
index 0000000..7c1a169
--- /dev/null
+++ b/tests/expectations/procedure_2_statements.txt
@@ -0,0 +1,2 @@
+5
+3
diff --git a/tests/expectations/procedure_print_argument.txt b/tests/expectations/procedure_print_argument.txt
new file mode 100644
index 0000000..7ed6ff8
--- /dev/null
+++ b/tests/expectations/procedure_print_argument.txt
@@ -0,0 +1 @@
+5
diff --git a/tests/procedure_2_statements.eln b/tests/procedure_2_statements.eln
new file mode 100644
index 0000000..447a9a1
--- /dev/null
+++ b/tests/procedure_2_statements.eln
@@ -0,0 +1,9 @@
+proc g()
+begin
+  writei(5);
+  writei(3)
+end;
+
+begin
+  g()
+end.
diff --git a/tests/procedure_definition.eln b/tests/procedure_definition.eln
index 94bbe85..fe500f5 100644
--- a/tests/procedure_definition.eln
+++ b/tests/procedure_definition.eln
@@ -1,4 +1,4 @@
-proc f; writei(5);
+proc f() writei(5);
 
 begin
   f()
diff --git a/tests/procedure_print_argument.eln b/tests/procedure_print_argument.eln
new file mode 100644
index 0000000..92ab218
--- /dev/null
+++ b/tests/procedure_print_argument.eln
@@ -0,0 +1,5 @@
+proc f(a: Int) writei(a);
+
+begin
+  f(5)
+end.
diff --git a/tests/tester.cpp b/tests/tester.cpp
index 6376aaa..284a67d 100755
--- a/tests/tester.cpp
+++ b/tests/tester.cpp
@@ -43,17 +43,33 @@ namespace elna
         return in_build_directory() / path;
     }
 
-    test_result run_for_output(boost::asio::io_context& context, const std::filesystem::path& binary,
-            std::initializer_list<boost::string_view> arguments)
+    boost::process::v2::process_stdio get_output_streams(const std::uint8_t stream_number,
+            boost::asio::readable_pipe& read_pipe)
+    {
+        if (stream_number == 1)
+        {
+            return boost::process::v2::process_stdio{ nullptr, read_pipe };
+        }
+        if (stream_number == 2)
+        {
+            return boost::process::v2::process_stdio{ nullptr, {}, read_pipe };
+        }
+        return boost::process::v2::process_stdio{ nullptr, read_pipe, read_pipe };
+    }
+
+    test_result run_for_output(boost::asio::io_context& context, const std::uint8_t stream_number,
+            const std::filesystem::path& binary, std::initializer_list<boost::string_view> arguments)
     {
         boost::asio::readable_pipe read_pipe{ context };
         test_result result{};
         std::string output;
         boost::asio::dynamic_string_buffer buffer = boost::asio::dynamic_buffer(output);
         boost::system::error_code ec;
+
+        boost::process::v2::process_stdio process_stdio;
         boost::process::v2::process elna_child(context,
                 binary, arguments,
-                boost::process::v2::process_stdio{ nullptr, read_pipe, read_pipe });
+                get_output_streams(stream_number, read_pipe));
         do
         {
             std::size_t transferred = read_pipe.read_some(buffer.prepare(512), ec);
@@ -84,7 +100,7 @@ namespace elna
         std::filesystem::remove(test_binary);
         std::filesystem::remove(test_object);
 
-        test_result result = run_for_output(context, "./build/bin/elna",
+        test_result result = run_for_output(context, 2, "./build/bin/elna",
                 { "-o", test_object.string(), test_entry.path().string() });
 
         if (result.code != 0)
@@ -157,7 +173,7 @@ namespace elna
         std::filesystem::path test_binary = in_build_directory(test_filename);
         test_binary.replace_extension();
 
-        return run_for_output(context,
+        return run_for_output(context, 1,
                 boost::process::search_path("qemu-riscv32"),
                 { test_binary.string() });
     }