diff --git a/common/rfb/CMsgReader.cxx b/common/rfb/CMsgReader.cxx
index c325d48..0271936 100644
--- a/common/rfb/CMsgReader.cxx
+++ b/common/rfb/CMsgReader.cxx
@@ -221,7 +221,7 @@
   rdr::U8 buf[width*height*4];
   rdr::U8* out;
 
-  if (width * height) {
+  if (width * height > 0) {
     pr = is->readU8();
     pg = is->readU8();
     pb = is->readU8();