diff --git a/scumm/string.cpp b/scumm/string.cpp
index f342547884c..22bdbb614ec 100644
--- a/scumm/string.cpp
+++ b/scumm/string.cpp
@@ -1110,7 +1110,7 @@ void CharsetRenderer::drawBits()
 			}
 		}
 		dst = (_dest_ptr += _vm->_realWidth);
-		mask += 40;
+		mask += _vm->gdi._numStrips;
 		y++;
 	}
 }