diff --git a/libvncclient/rfbproto.c b/libvncclient/rfbproto.c
index 808ad4d..8d6a4c1 100644
--- a/libvncclient/rfbproto.c
+++ b/libvncclient/rfbproto.c
@@ -1879,7 +1879,7 @@ HandleRFBServerMessage(rfbClient* client)
 	/* Regardless of cause, do not divide by zero. */
 	linesToRead = bytesPerLine ? (RFB_BUFFER_SIZE / bytesPerLine) : 0;
 
-	while (h > 0) {
+	while (linesToRead && h > 0) {
 	  if (linesToRead > h)
 	    linesToRead = h;