diff --git a/tools/build/makeshorewall b/tools/build/makeshorewall
index a222a16d3..6b1b000ac 100644
--- a/tools/build/makeshorewall
+++ b/tools/build/makeshorewall
@@ -535,7 +535,7 @@ fi
 if [ -n "$OLDVERSION" ]; then
     progress_message "Creating patch-$VERSION ..."
 
-    diff -Nau shorewall-$OLDVERSION shorewall-$VERSION > patch-$VERSION
+    diff -Naur shorewall-$OLDVERSION shorewall-$VERSION > patch-$VERSION
 fi
 
 progress_message "Shorewall $VERSION Build complete - $(date)"