diff --git a/build.sh b/build.sh
index 12075ed..2130553 100755
--- a/build.sh
+++ b/build.sh
@@ -76,6 +76,7 @@ gcc src/main.c src/debug.c \
 	temp/objects/o_string.o \
 	temp/runtime/runtime.o \
 	temp/runtime/runtime_error.o \
+	temp/runtime/o_func.o \
 	temp/common/executable.o \
 	-o build/noja $FLAGS -Lbuild/ -lnoja-compile -lnoja-objects -lxjson
 
diff --git a/samples/func.noja b/samples/func.noja
new file mode 100644
index 0000000..6b0595c
--- /dev/null
+++ b/samples/func.noja
@@ -0,0 +1,7 @@
+
+fun hello() 
+	{
+		print;('hello');
+	}
+
+return hello;
\ No newline at end of file
diff --git a/src/common/executable.c b/src/common/executable.c
index d6bbb66..0ea4510 100644
--- a/src/common/executable.c
+++ b/src/common/executable.c
@@ -57,6 +57,7 @@ static const InstrInfo instr_table[] = {
 	[OPCODE_PUSHTRU] = {"PUSHTRU", 0, NULL},
 	[OPCODE_PUSHFLS] = {"PUSHFLS", 0, NULL},
 	[OPCODE_PUSHNNE] = {"PUSHNNE", 0, NULL},
+	[OPCODE_PUSHFUN] = {"PUSHFUN", 2, (OperandType[]) {OPTP_INT, OPTP_INT}},
 
 	[OPCODE_RETURN] = {"RETURN", 0, NULL},
 
@@ -319,7 +320,7 @@ _Bool ExeBuilder_Append(ExeBuilder *exeb, Error *error, Opcode opcode, Operand *
 			// ERROR: Too many operands were provided.
 			Error_Report(error, 0, 
 				"Instruction %s expects %d operands, but %d were provided", 
-				info->name, opc, info->opcount);
+				info->name, info->opcount, opc);
 			return 0;
 		}
 
diff --git a/src/common/executable.h b/src/common/executable.h
index 83079e6..fa49ed9 100644
--- a/src/common/executable.h
+++ b/src/common/executable.h
@@ -37,6 +37,7 @@ typedef enum {
 	OPCODE_PUSHTRU,
 	OPCODE_PUSHFLS,
 	OPCODE_PUSHNNE,
+	OPCODE_PUSHFUN,
 	OPCODE_RETURN,
 	OPCODE_JUMPIFNOTANDPOP,
 	OPCODE_JUMP,
diff --git a/src/compiler/ASTi.h b/src/compiler/ASTi.h
index 840c6bf..79e7f36 100644
--- a/src/compiler/ASTi.h
+++ b/src/compiler/ASTi.h
@@ -9,6 +9,8 @@ typedef enum {
 	NODE_IFELSE,
 	NODE_COMP,
 	NODE_RETURN,
+	NODE_FUNC,
+	NODE_ARG,
 } NodeKind;
 
 typedef enum {
@@ -93,4 +95,17 @@ typedef struct {
 	Node base;
 	Node *val;
 } ReturnNode;
+
+typedef struct {
+	Node  base;
+	char *name;
+	Node *argv;
+	int   argc;
+	Node *body;
+} FunctionNode;
+
+typedef struct {
+	Node  base;
+	char *name;
+} ArgumentNode;
 #endif
\ No newline at end of file
diff --git a/src/compiler/compile.c b/src/compiler/compile.c
index b6b7c31..206d470 100644
--- a/src/compiler/compile.c
+++ b/src/compiler/compile.c
@@ -241,6 +241,86 @@ static _Bool emit_instr_for_node(ExeBuilder *exeb, Node *node, Error *error)
 				return 1;
 			}
 
+			case NODE_FUNC:
+			{
+				FunctionNode *func = (FunctionNode*) node;
+
+				Promise *func_index = Promise_New(ExeBuilder_GetAlloc(exeb), sizeof(long long int));
+				Promise *jump_index = Promise_New(ExeBuilder_GetAlloc(exeb), sizeof(long long int));
+
+				if(func_index == NULL || jump_index == NULL)
+					{
+						Error_Report(error, 1, "No memory");
+						return 0;
+					}
+
+				// Push function.
+				{
+					Operand ops[2] = {
+						{ .type = OPTP_PROMISE, .as_promise = func_index },
+						{ .type = OPTP_INT,     .as_int     = func->argc },
+					};
+
+					if(!ExeBuilder_Append(exeb, error, OPCODE_PUSHFUN, ops, 2, func->base.offset, func->base.length))
+						return 0;
+				}
+				
+				// Assign variable.
+				Operand op = (Operand) { .type = OPTP_STRING, .as_string = func->name };
+				if(!ExeBuilder_Append(exeb, error, OPCODE_ASS, &op, 1,  func->base.offset, func->base.length))
+					return 0;
+
+				// Pop function object.
+				op = (Operand) { .type = OPTP_INT, .as_int = 1 };
+				if(!ExeBuilder_Append(exeb, error, OPCODE_POP, &op, 1,  func->base.offset, func->base.length))
+					return 0;
+
+				// Jump after the function code.
+				op = (Operand) { .type = OPTP_PROMISE, .as_promise = jump_index };
+				if(!ExeBuilder_Append(exeb, error, OPCODE_JUMP, &op, 1,  func->base.offset, func->base.length))
+					return 0;
+
+				// This is the function code index.
+				long long int temp = ExeBuilder_InstrCount(exeb);
+				Promise_Resolve(func_index, &temp, sizeof(temp));
+
+				// Compile the function body.
+				{
+					// Assign the arguments.
+
+					if(func->argv)
+						assert(func->argv->kind == NODE_ARG);
+
+					ArgumentNode *arg = (ArgumentNode*) func->argv;
+
+					while(arg)
+						{
+							op = (Operand) { .type = OPTP_STRING, .as_string = arg->name };
+							if(!ExeBuilder_Append(exeb, error, OPCODE_ASS, &op, 1,  arg->base.offset, arg->base.length))
+								return 0;
+
+							op = (Operand) { .type = OPTP_INT, .as_int = 1 };
+							if(!ExeBuilder_Append(exeb, error, OPCODE_POP, &op, 1,  arg->base.offset, arg->base.length))
+								return 0;
+
+							assert(arg->base.next->kind == NODE_ARG);
+
+							arg = (ArgumentNode*) arg->base.next;
+						}
+
+					if(!emit_instr_for_node(exeb, func->body, error))
+						return 0;
+				}
+
+				// This is the first index after the function code.
+				temp = ExeBuilder_InstrCount(exeb);
+				Promise_Resolve(jump_index, &temp, sizeof(temp));
+
+				Promise_Free(func_index);
+				Promise_Free(jump_index);
+				return 1;
+			}
+
 			default:
 			UNREACHABLE;
 			return 0;
diff --git a/src/compiler/parse.c b/src/compiler/parse.c
index 0fe9640..67b45c2 100644
--- a/src/compiler/parse.c
+++ b/src/compiler/parse.c
@@ -25,6 +25,7 @@ typedef enum {
 	TIDENT,
 
 	TKWIF,
+	TKWFUN,
 	TKWELSE,
 	TKWNONE,
 	TKWTRUE,
@@ -51,6 +52,7 @@ static Node *parse_expression(Context *ctx);
 static Node *parse_expression_statement(Context *ctx);
 static Node *parse_ifelse_statement(Context *ctx);
 static Node *parse_compound_statement(Context *ctx, TokenKind end);
+static Node *parse_function_definition(Context *ctx);
 
 static inline _Bool isoper(char c)
 {
@@ -125,6 +127,10 @@ AST *parse(Source *src, BPAlloc *alloc, Error *error)
 						{
 							tok->kind = TKWIF;
 						}
+					else if(matchstr(str + tok->offset, tok->length, "fun"))
+						{
+							tok->kind = TKWFUN;
+						}
 					else if(matchstr(str + tok->offset, tok->length, "else"))
 						{
 							tok->kind = TKWELSE;
@@ -397,6 +403,9 @@ static Node *parse_statement(Context *ctx)
 				node->val = val;
 				return (Node*) node;
 			}
+
+			case TKWFUN:
+			return parse_function_definition(ctx);
 		}
 
 	Error_Report(ctx->error, 0, "Got token \"%.*s\" where the start of a statement was expected", 
@@ -551,6 +560,20 @@ static Node *parse_string_primary_expression(Context *ctx)
 	return (Node*) node;
 }
 
+static char *copy_token_text(Context *ctx)
+{
+	char *copy = BPAlloc_Malloc(ctx->alloc, ctx->token->length + 1);
+
+	if(copy == NULL)
+		return NULL;
+
+	memcpy(copy, ctx->src + ctx->token->offset, ctx->token->length);
+
+	copy[ctx->token->length] = '\0';
+
+	return copy;
+}
+
 static Node *parse_primary_expresion(Context *ctx)
 {
 	assert(ctx != NULL);
@@ -789,23 +812,14 @@ static Node *parse_primary_expresion(Context *ctx)
 
 			case TIDENT:
 			{
-				char *copy;
-				int   copyl;
+				char *copy  = copy_token_text(ctx);
+				int   copyl = ctx->token->length;
 
-				{
-					copy = BPAlloc_Malloc(ctx->alloc, ctx->token->length + 1);
-
-					if(copy == NULL)
-						{
-							Error_Report(ctx->error, 1, "No memory");
-							return NULL;
-						}
-
-					copyl = ctx->token->length;
-					memcpy(copy, ctx->src + ctx->token->offset, copyl);
-					copy[copyl] = '\0';
-					
-				}
+				if(copy == NULL)
+					{
+						Error_Report(ctx->error, 1, "No memory");
+						return NULL;
+					}
 
 				IdentExprNode *node;
 				{
@@ -966,7 +980,6 @@ static Node *parse_expression(Context *ctx)
 static Node *parse_ifelse_statement(Context *ctx)
 {
 	assert(ctx != NULL);
-	assert(ctx->token != NULL);
 
 	if(done(ctx))
 		{
@@ -1076,4 +1089,159 @@ static Node *parse_compound_statement(Context *ctx, TokenKind end)
 	}
 
 	return (Node*) node;
+}
+
+static Node *parse_function_definition(Context *ctx)
+{
+	assert(ctx != NULL);
+
+	if(done(ctx))
+		{
+			Error_Report(ctx->error, 0, "Source ended where a function definition was expected");
+			return NULL;
+		}
+
+	if(current(ctx) != TKWFUN)
+		{
+			Error_Report(ctx->error, 0, "Got unexpected token \"%.*s\" where a function definition was expected", ctx->token->length, ctx->src + ctx->token->offset);
+			return NULL;
+		}
+
+	int offset = current_token(ctx)->offset;
+
+	if(next(ctx) != TIDENT)
+		{
+			if(done(ctx))
+				Error_Report(ctx->error, 0, "Source ended where an identifier was expected as function name");
+			else
+				Error_Report(ctx->error, 0, "Got unexpected token \"%.*s\" where an identifier was expected as function name", ctx->token->length, ctx->src + ctx->token->offset);
+			return NULL;
+		}
+
+	char *name = copy_token_text(ctx);
+
+	if(name == NULL)
+		{
+			Error_Report(ctx->error, 1, "No memory");
+			return NULL;
+		}
+
+	if(next(ctx) != '(')
+		{
+			if(done(ctx))
+				Error_Report(ctx->error, 0, "Source ended where a function argument list was expected");
+			else
+				Error_Report(ctx->error, 0, "Got unexpected token \"%.*s\" where a function argument list was expected", ctx->token->length, ctx->src + ctx->token->offset);
+			return NULL;
+		}
+
+	Node *argv = NULL;
+	int   argc = 0;
+
+	if(next(ctx) != ')')
+		{
+			// Parse arguments.
+
+			while(1)
+				{
+					if(done(ctx))
+						{
+							Error_Report(ctx->error, 0, "Source ended inside a function argument list");
+							return NULL;
+						}
+
+					if(current(ctx) != TIDENT)
+						{
+							Error_Report(ctx->error, 0, "Got unexpected token \"%.*s\" where a function argument name was expected", ctx->token->length, ctx->src + ctx->token->offset);
+							return NULL;
+						}
+
+					char *arg_name = copy_token_text(ctx);
+
+					if(arg_name == NULL)
+						{
+							Error_Report(ctx->error, 1, "No memory");
+							return NULL;
+						}
+
+					ArgumentNode *arg;
+					{
+						// Make argument node.
+						arg = BPAlloc_Malloc(ctx->alloc, sizeof(ArgumentNode));
+
+						if(arg == NULL)
+							{
+								Error_Report(ctx->error, 1, "No memory");
+								return NULL;
+							}
+
+						arg->base.kind = NODE_ARG;
+						arg->base.next = NULL;
+						arg->base.offset = current_token(ctx)->offset;
+						arg->base.length = current_token(ctx)->length;
+						arg->name = arg_name;
+					}
+
+					// Add it to the list.
+					argc += 1;
+					arg->base.next = argv;
+					argv = (Node*) arg;
+
+					// Get either ',' or ')'.
+
+					if(next(ctx) == ')')
+						break;
+
+					if(done(ctx))
+						{
+							Error_Report(ctx->error, 0, "Source ended inside a function argument list");
+							return NULL;
+						}
+
+					if(current(ctx) != ',')
+						{
+							Error_Report(ctx->error, 0, "Got unexpected token \"%.*s\" where inside function argument list, where either ',' or ')' were expected", ctx->token->length, ctx->src + ctx->token->offset);
+							return NULL;
+						}
+
+					// Now prepare for the next identifier.
+					next(ctx);
+				}
+		}
+
+	next(ctx); // Consume the ')'.
+
+	if(done(ctx))
+		{
+			Error_Report(ctx->error, 0, "Source ended before function body");
+			return NULL;
+		}
+
+	Node *body = parse_statement(ctx);
+
+	if(body == NULL)
+		return NULL;
+
+	FunctionNode *func;
+	{
+		// Make argument node.
+		func = BPAlloc_Malloc(ctx->alloc, sizeof(FunctionNode));
+
+		if(func == NULL)
+			{
+				Error_Report(ctx->error, 1, "No memory");
+				return NULL;
+			}
+
+		func->base.kind = NODE_FUNC;
+		func->base.next = NULL;
+		func->base.offset = offset;
+		func->base.length = body->offset + body->length - offset;
+		func->name = name;
+		func->argv = argv;
+		func->argc = argc;
+		func->body = body;
+	}
+
+	return (Node*) func;
 }
\ No newline at end of file
diff --git a/src/runtime/o_func.c b/src/runtime/o_func.c
index b739b7a..704680f 100644
--- a/src/runtime/o_func.c
+++ b/src/runtime/o_func.c
@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <stdlib.h>
 #include "../utils/defs.h"
 #include "../objects/objects.h"
 #include "runtime.h"
@@ -7,7 +8,7 @@ typedef struct {
 	Object base;
 	Runtime *runtime;
 	Executable *exe;
-	int index;
+	int index, argc;
 } FunctionObject;
 
 static Object *call(Object *self, Object **argv, unsigned int argc, Heap *heap, Error *error);
@@ -28,16 +29,64 @@ static Object *call(Object *self, Object **argv, unsigned int argc, Heap *heap,
 	FunctionObject *func = (FunctionObject*) self;
 
 	assert(func->exe != NULL);
+	assert(func->argc >= 0);
 	assert(func->index >= 0);
 
-	return run(func->runtime, error, func->exe, func->index, argv, argc);	
+	// Make sure the right amount of arguments is provided.
+
+	Object **argv2;
+
+	int expected_argc = func->argc;
+
+	if(expected_argc < (int) argc)
+		{
+			// Nothing to be done. By using
+			// the right argc the additional
+			// arguments are ignored implicitly.
+			argv2 = argv;
+		}
+	else if(expected_argc > (int) argc)
+		{
+			// Some arguments are missing.
+			argv2 = malloc(sizeof(Object*) * expected_argc);
+
+			if(argv2 == NULL)
+				{
+					Error_Report(error, 1, "No memory");
+					return NULL;
+				}
+
+			// Copy the provided arguments.
+			for(int i = 0; i < (int) argc; i += 1)
+				argv2[i] = argv[i];
+
+			// Set the unspecified arguments to none.
+			for(int i = argc; i < expected_argc; i += 1)
+				{
+					argv2[i] = Object_NewNone(heap, error);
+
+					if(argv2[i] == NULL)
+						return 0;
+				}
+		}
+	else
+		// The right amount of arguments was provided.
+		argv2 = argv;
+
+	Object *result = run(func->runtime, error, func->exe, func->index, argv2, expected_argc);
+
+	if(argv2 != argv)
+		free(argv2);
+
+	return result;
 }
 
-Object *Object_FromNojaFunction(Runtime *runtime, Executable *exe, int index, Heap *heap, Error *error)
+Object *Object_FromNojaFunction(Runtime *runtime, Executable *exe, int index, int argc, Heap *heap, Error *error)
 {
 	assert(runtime != NULL);
 	assert(exe != NULL);
 	assert(index >= 0);
+	assert(argc >= 0);
 	assert(heap != NULL);
 	assert(error != NULL);
 
@@ -57,5 +106,7 @@ Object *Object_FromNojaFunction(Runtime *runtime, Executable *exe, int index, He
 	func->runtime = runtime;
 	func->exe = exe_copy;
 	func->index = index;
+	func->argc = argc;
+
 	return (Object*) func;
 }
\ No newline at end of file
diff --git a/src/runtime/runtime.c b/src/runtime/runtime.c
index cabe980..9d668f0 100644
--- a/src/runtime/runtime.c
+++ b/src/runtime/runtime.c
@@ -531,6 +531,22 @@ static _Bool step(Runtime *runtime, Error *error)
 				return 1;
 			}
 
+			case OPCODE_PUSHFUN:
+			{
+				assert(opc == 2);
+				assert(ops[0].type == OPTP_INT);
+				assert(ops[1].type == OPTP_INT);
+
+				Object *obj = Object_FromNojaFunction(runtime, runtime->frame->exe, ops[0].as_int, ops[1].as_int, runtime->heap, error);
+				
+				if(obj == NULL)
+					return 0;
+
+				if(!Runtime_Push(runtime, error, obj))
+					return 0;
+				return 1;
+			}
+
 			case OPCODE_RETURN:
 			return 0;
 
diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h
index 2c1cec6..1c4a92e 100644
--- a/src/runtime/runtime.h
+++ b/src/runtime/runtime.h
@@ -20,5 +20,5 @@ void 	  Snapshot_Print(Snapshot *snapshot, FILE *fp);
 
 Object *run(Runtime *runtime, Error *error, Executable *exe, int index, Object **argv, int argc);
 
-Object *Object_FromNojaFunction(Runtime *runtime, Executable *exe, int offset, Heap *heap, Error *error);
+Object *Object_FromNojaFunction(Runtime *runtime, Executable *exe, int index, int argc, Heap *heap, Error *error);
 #endif
\ No newline at end of file