diff --git a/wrapper b/wrapper
index 5cf6ebf..d64ff77 100755
--- a/wrapper
+++ b/wrapper
@@ -80,7 +80,7 @@ fi
 
 dia_command=$1
 shift
-if [ $# -eq 1 -a "$1" -eq "-d" ]; then
+if [ $# -eq 1 ] && [ "$1" == "-d" ]; then
   export option="-d"
 fi