diff --git a/README.md b/README.md
index bbec671..c15d6a2 100644
--- a/README.md
+++ b/README.md
@@ -19,83 +19,5 @@ and a possbility to compile Elna programs for different platforms.
 
 ## Grammar
 
-```ebnf
-digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
-letter = "A" | "B" | … | "Z" | "a" | "b" | … | "z";
-
-ident = letter { letter | digit | "_" };
-integer = digit { digit };
-float = integer "." integer;
-boolean = "true" | "false";
-
-literal = integer | float | boolean | "'" character "'" | """ { character } """;
-
-program = [ "type" type_definitions ";" ]
-    [ constant_part ]
-    { procedure_definition }
-    [ variable_part ]
-    "begin" [ statement_list ] "end" ".";
-
-procedure_definition = "proc" ident formal_parameter_list ";" ( block | "extern" ) ";";
-
-block = [ constant_part ]
-    [ variable_part ]
-    statement;
-
-constant_part = "const" ident "=" integer { "," ident "=" integer } ";";
-variable_part = "var" variable_declarations ";";
-
-statement = ident ":=" expression
-          | ident actual_parameter_list
-          | while_do
-          | if_then_else;
-
-
-while_do = "while" condition "do" [ statement_list ] "end";
-if_then_else = "if" expression
-    "then" [ statement_list ]
-    [ else statement_list ] "end";
-
-statement_list = statement {";" statement };
-
-condition = "odd" expression |
-            expression ("="|"#"|"<"|"<="|">"|">=") expression;
-
-comparison_operator = "=", "<>", "<", ">", "<=", ">=";
-unary_prefix = "not", "@";
-
-expression = logical_operand { ("and" | "or") logical_operand };
-logical_operand = comparand { comparison_operator comparand };
-comparand = summand { ("+" | "-") summand };
-summand = factor { ("*" | "/") factor };
-factor = pointer { unary_prefix pointer };
-
-pointer = literal
-        | designator_expression { $$ = $1; }
-        | "(" expression ")";
-
-designator_expression = designator_expression "[" expression "]"
-                      | designator_expression "." ident
-                      | designator_expression "^"
-                      | ident;
-
-formal_parameter_list = "(" [ variable_declarations ] ")";
-
-actual_parameter_list = "(" [ expressions ] ")";
-
-expressions = expression { "," expression };
-
-variable_declarations = variable_declaration { ";" variable_declaration };
-
-variable_declaration = ident ":" type_expression;
-
-type_expression = "array" integer "of" type_expression
-                | "pointer" "to" type_expression
-                | "record" field_list "end"
-                | "union" field_list "end"
-                | ident;
-
-field_list = field_declaration { ";" field_declaration };
-
-field_declaration = ident ":" type_expression;
-```
+Flex and bison grammar specifications, `lexer.ll` and `parser.yy`, can be found
+in the `boot/` directory.
diff --git a/gcc/elna-generic.cc b/gcc/elna-generic.cc
index ad9ab53..229255c 100644
--- a/gcc/elna-generic.cc
+++ b/gcc/elna-generic.cc
@@ -699,20 +699,23 @@ namespace gcc
             this->current_expression = error_mark_node;
             return;
         }
-        if (TREE_TYPE(this->current_expression) != TREE_TYPE(lvalue))
+        if (TREE_TYPE(this->current_expression) == TREE_TYPE(lvalue)
+                || (is_pointer_type(TREE_TYPE(lvalue)) && this->current_expression == null_pointer_node))
+        {
+            tree assignment = build2_loc(statement_location, MODIFY_EXPR,
+                    void_type_node, lvalue, this->current_expression);
+
+            append_to_statement_list(assignment, &this->current_statements);
+            this->current_expression = NULL_TREE;
+        }
+        else
         {
             error_at(statement_location,
                     "cannot assign value of type %s to variable of type %s",
                     print_type(TREE_TYPE(this->current_expression)),
                     print_type(TREE_TYPE(lvalue)));
             this->current_expression = error_mark_node;
-            return;
         }
-        auto assignment = build2_loc(statement_location, MODIFY_EXPR,
-                void_type_node, lvalue, this->current_expression);
-
-        append_to_statement_list(assignment, &this->current_statements);
-        this->current_expression = NULL_TREE;
     }
 
     void generic_visitor::visit(boot::if_statement *statement)