diff --git a/SMILEBASIC/VM.d b/SMILEBASIC/VM.d
index 10d3d41..fd06259 100644
--- a/SMILEBASIC/VM.d
+++ b/SMILEBASIC/VM.d
@@ -2161,3 +2161,11 @@ class SetX : Code
             vm.petitcomputer.xoff(func);
     }
 }
+
+class Pop : Code
+{
+    override void execute(VM vm)
+    {
+        vm.decSP();
+    }
+}
diff --git a/SMILEBASIC/compiler.d b/SMILEBASIC/compiler.d
index b45b538..c9d997c 100644
--- a/SMILEBASIC/compiler.d
+++ b/SMILEBASIC/compiler.d
@@ -697,8 +697,13 @@ class Compiler
                     genCode(new PopVarExpression(sc));
                 }
                 break;
-                default:
-                    throw new SyntaxError();
+            case NodeType.VoidExpression:
+                {
+                    genCode(new Pop());
+                }
+                break;
+            default:
+                throw new SyntaxError();
 
         }
     }
diff --git a/SMILEBASIC/parser.d b/SMILEBASIC/parser.d
index f2d1c82..5e3d0fa 100644
--- a/SMILEBASIC/parser.d
+++ b/SMILEBASIC/parser.d
@@ -970,18 +970,30 @@ class Parser
                         while(true)
                         {
                             token = lex.front();
-                            Expression arg = expression();
-                            if(!isLValue(arg))
+                            if (token.type == TokenType.Comma)
                             {
-                                //to support func args... OUT (no argument)
-                                if (!func.outVariable.length)
+                                func.addOut(new VoidExpression(lex.location));
+                            }
+                            else
+                            {
+                                Expression arg = expression();
+                                if (!arg)
                                 {
+                                    func.addOut(new VoidExpression(lex.location));
                                     break;
                                 }
-                                syntaxError();
-                                return null;
+                                if(!isLValue(arg))
+                                {
+                                    //to support func args... OUT (no argument)
+                                    if (!func.outVariable.length)
+                                    {
+                                        break;
+                                    }
+                                    syntaxError();
+                                    return null;
+                                }
+                                func.addOut(arg);
                             }
-                            func.addOut(arg);
                             token = lex.front();
                             if(token.type == TokenType.Comma)
                             {