diff --git a/src/gb/gbGfx.cpp b/src/gb/gbGfx.cpp
index a197405f..72e65598 100644
--- a/src/gb/gbGfx.cpp
+++ b/src/gb/gbGfx.cpp
@@ -234,7 +234,7 @@ void gbRenderLine()
 
       if(y >= inUseRegister_WY) {
 
-        if (gbWindowLine>143)
+        if ((gbWindowLine == -1) || (gbWindowLine>144))
           gbWindowLine = 0;
 
         int wx = register_WX;