diff --git a/lib/src/libc/bootstrap.gsc b/lib/src/libc/bootstrap.gsc
index aaeeeaf..799f16b 100644
--- a/lib/src/libc/bootstrap.gsc
+++ b/lib/src/libc/bootstrap.gsc
@@ -8,7 +8,8 @@ include "os"
 fun main()
 
 # entrypoint function
+#[nomangle,noreturn,entry]
 fun _start() {
     main()
-    _exit(0 as i32)
+    os::exit(0 as i32)
 }
diff --git a/lib/src/libc/os.gsc b/lib/src/libc/os.gsc
index bb12636..954a374 100644
--- a/lib/src/libc/os.gsc
+++ b/lib/src/libc/os.gsc
@@ -2,4 +2,10 @@
 include "types"
 
 # from unistd.h
+#[nomangle,preserve,noreturn]
 fun _exit(in i32: code)
+
+#[noreturn]
+fun exit(in i32: code) {
+    os::_exit(code)
+}
diff --git a/src/ast/ast.c b/src/ast/ast.c
index 67f841a..012581f 100644
--- a/src/ast/ast.c
+++ b/src/ast/ast.c
@@ -93,6 +93,7 @@ void AST_init() {
     lookup_table[AST_Dereference] = "deref";
     lookup_table[AST_Reference]   = "ref";
     lookup_table[AST_Return]      = "ret";
+    lookup_table[AST_ModuleRef]   = "modref";
 }
 
 const char* AST_node_to_string(const struct AST_Node_t* node) {
diff --git a/src/ast/ast.h b/src/ast/ast.h
index d4b8b8d..adb71a5 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -85,6 +85,7 @@ enum AST_SyntaxElement_t {
     AST_Include,
     AST_Char,
     AST_Return,
+    AST_ModuleRef,
     AST_ELEMENT_COUNT
 };
 
diff --git a/src/cfg/opt.c b/src/cfg/opt.c
index 559cc66..97c837a 100644
--- a/src/cfg/opt.c
+++ b/src/cfg/opt.c
@@ -180,6 +180,7 @@ char* module_ref_to_str(ModuleRef* ref) {
 
             if (n + 1 < ref->module_path->len) {
                 g_string_append_unichar(string, ':');
+                g_string_append_unichar(string, ':');
             }
         }
     }
diff --git a/src/lex/lexer.l b/src/lex/lexer.l
index 9902ea4..9f28ba3 100644
--- a/src/lex/lexer.l
+++ b/src/lex/lexer.l
@@ -6,11 +6,11 @@
     #include <mem/cache.h>
 
     int yyLineNumber = 1;
-  
+
     int yylex();
 
     extern int yyerror(const char* s);
-  
+
     #define YY_USER_ACTION beginToken(yytext);
 
     #define YY_INPUT(buf,result,max_size)  {\
@@ -30,6 +30,7 @@
 
 #.* ;
 
+"::" {return(ModSep);};
 ":" {DEBUG("\"%s\" tokenized with \':\'", yytext); return(':');};
 "=" {DEBUG("\"%s\" tokenized with \'=\'", yytext); return('=');};
 "+" {DEBUG("\"%s\" tokenized with \'+\'", yytext); return('+');};
@@ -57,7 +58,7 @@
 "short" {DEBUG("\"%s\" tokenized with \'KeyShort\'", yytext); return(KeyShort);};
 "long" {DEBUG("\"%s\" tokenized with \'KeyLong\'", yytext); return(KeyLong);};
 "half" {DEBUG("\"%s\" tokenized with \'KeyHalf\'", yytext); return(KeyHalf);};
-"double" {DEBUG("\"%s\" tokenized with \'KeyDouble\'", yytext); return(KeyDouble);}; 
+"double" {DEBUG("\"%s\" tokenized with \'KeyDouble\'", yytext); return(KeyDouble);};
 "signed" {DEBUG("\"%s\" tokenized with \'KeySigned\'", yytext); return(KeySigned);};
 "unsigned" {DEBUG("\"%s\" tokenized with \'KeyUnsigned\'", yytext); return(KeyUnsigned);};
 "ref" {DEBUG("\"%s\" tokenized with \'KeyRef\'", yytext); return(KeyRef);};
@@ -106,7 +107,7 @@
 \"([^\"\n])*\" {
     yytext = yytext +1;
     yytext[yyleng - 2] = 0;
-    
+
     DEBUG("\"%s\" tokenized with \'ValStr\'", yytext);
     yylval.string = collapse_escape_sequences(yytext);
     return(ValStr);
diff --git a/src/set/set.c b/src/set/set.c
index c2714e3..8cf746c 100644
--- a/src/set/set.c
+++ b/src/set/set.c
@@ -2083,6 +2083,27 @@ Parameter get_param_from_func(Function* func, size_t index) {
     }
 }
 
+char* module_ref_to_string(AST_NODE_PTR node) {
+    switch (node->kind) {
+        case AST_Ident:
+            return mem_strdup(MemoryNamespaceSet, node->value);
+        case AST_ModuleRef:
+
+            char* submodule = module_ref_to_string(AST_get_last_node(node));
+            char* curmodule = module_ref_to_string(AST_get_node(node, 0));
+
+            char* composed = g_strjoin("::", curmodule, submodule, NULL);
+            char* cached_composed = mem_strdup(MemoryNamespaceSet, composed);
+            mem_free(composed);
+            mem_free(curmodule);
+            mem_free(submodule);
+
+            return cached_composed;
+        default:
+            return NULL;
+    }
+}
+
 int createfuncall(FunctionCall* funcall, AST_NODE_PTR currentNode) {
     assert(currentNode != NULL);
     assert(currentNode->children->len == 2);
@@ -2090,12 +2111,14 @@ int createfuncall(FunctionCall* funcall, AST_NODE_PTR currentNode) {
     AST_NODE_PTR argsListNode = AST_get_node(currentNode, 1);
     AST_NODE_PTR nameNode     = AST_get_node(currentNode, 0);
 
+    char* function_name = module_ref_to_string(nameNode);
+
     Function* fun = NULL;
-    if (nameNode->kind == AST_Ident) {
-        int result = getFunction(nameNode->value, &fun);
+    if (nameNode->kind == AST_ModuleRef || nameNode->kind == AST_Ident) {
+        int result = getFunction(function_name, &fun);
         if (result == SEMANTIC_ERROR) {
             print_diagnostic(&currentNode->location, Error,
-                             "Unknown function: `%s`", nameNode->value);
+                             "Unknown function: `%s`", function_name);
             return SEMANTIC_ERROR;
         }
     }
@@ -2107,10 +2130,8 @@ int createfuncall(FunctionCall* funcall, AST_NODE_PTR currentNode) {
         // unique
         const char* boxName =
           AST_get_node(nameNode, (nameNode->children->len - 2))->value;
-        const char* funName =
-          AST_get_node(nameNode, (nameNode->children->len - 1))->value;
 
-        const char* name = g_strjoin("", boxName, ".", funName, NULL);
+        const char* name = g_strjoin("", boxName, ".", function_name, NULL);
 
         int result = getFunction(name, &fun);
         if (result) {
@@ -2629,7 +2650,7 @@ int createFunction(Function* function, AST_NODE_PTR currentNode) {
 
     // compose function name by appending parent modules
     char* modules = module_ref_to_str(currentNode->location.module_ref);
-    char* composed_name = g_strjoin("", modules, ":", function->name, NULL);
+    char* composed_name = g_strjoin("", modules, "::", function->name, NULL);
     g_free(modules);
     function->name = composed_name;
 
diff --git a/src/yacc/parser.y b/src/yacc/parser.y
index 46f4477..cf83f51 100644
--- a/src/yacc/parser.y
+++ b/src/yacc/parser.y
@@ -77,6 +77,7 @@
 %type <node_ptr> program
 %type <node_ptr> storage_expr
 %type <node_ptr> returnstmt
+%type <node_ptr> moduleref
 
 
 %token KeyInt
@@ -128,6 +129,7 @@
 %token FunExtsupport
 %token Invalid
 %token KeyReturn
+%token ModSep
 
 /* Operator associativity */
 /* Operators at lower line number have lower precedence */
@@ -162,7 +164,11 @@ programbody: moduleimport {$$ = $1;}
        | decl{$$ = $1;}
        | typedef{$$ = $1;};
 
-
+moduleref: Ident {$$ = AST_new_node(new_loc(), AST_Ident, $1);}
+        | Ident ModSep moduleref {AST_NODE_PTR modref = AST_new_node(new_loc(), AST_ModuleRef, NULL);
+                                   AST_push_node(modref, AST_new_node(new_loc(), AST_Ident, $1));
+                                   AST_push_node(modref, $3);
+                                   $$ = modref;};
 
 expr: ValFloat {$$ = AST_new_node(new_loc(), AST_Float, $1);}
     | ValInt    {$$ = AST_new_node(new_loc(), AST_Int, $1);}
@@ -352,9 +358,8 @@ reinterpretcast: expr KeyTo type %prec KeyTo { AST_NODE_PTR cast = AST_new_node(
                                     DEBUG("Reinterpret-Cast"); };
 
 
-funcall: Ident argumentlist {AST_NODE_PTR funcall = AST_new_node(new_loc(), AST_Call, NULL);
-                             AST_NODE_PTR ident = AST_new_node(new_loc(), AST_Ident, $1);
-                             AST_push_node(funcall, ident);
+funcall: moduleref argumentlist {AST_NODE_PTR funcall = AST_new_node(new_loc(), AST_Call, NULL);
+                             AST_push_node(funcall, $1);
                              AST_push_node(funcall, $2);
                              $$ = funcall;
                              DEBUG("Function call"); };