diff --git a/SMILEBASIC/builtinfunctions.d b/SMILEBASIC/builtinfunctions.d
index 26b989f..79133d6 100644
--- a/SMILEBASIC/builtinfunctions.d
+++ b/SMILEBASIC/builtinfunctions.d
@@ -398,7 +398,7 @@ class BuiltinFunction
     static void GCLS(PetitComputer p, DefaultValue!(int, false) color)
     {
         color.setDefaultValue(0);
-        p.graphic.gfill(p.graphic.useGRP, 0, 0, 511, 511, cast(int)color);
+        p.graphic.gcls(p.graphic.useGRP, cast(int)color);
     }
     static void GPSET(PetitComputer p, int x, int y, DefaultValue!(int, false) color)
     {
diff --git a/SMILEBASIC/graphic.d b/SMILEBASIC/graphic.d
index 3be2ed9..2064415 100644
--- a/SMILEBASIC/graphic.d
+++ b/SMILEBASIC/graphic.d
@@ -646,6 +646,10 @@ class Graphic
     {
         sendDrawMessage(DrawType.FILL, cast(byte)page, cast(short)x, cast(short)y, cast(short)x2, cast(short)y2, color);
     }
+    void gcls(int page, uint color)
+    {
+        sendDrawMessage(DrawType.FILL, cast(byte)page, 0, 0, cast(short)width, cast(short)height, color);
+    }
     void gpaint(int page, int x, int y, uint color)
     {
         sendDrawMessage(DrawType.PAINT, cast(byte)page, cast(short)x, cast(short)y, color);