diff --git a/maskdyads b/maskdyads
index 6e5efca180b91dfdc900dbcc4ecb73abd85aa62b..de80def5dfd32e9f286903190bad1630d6ed10d2 100755
--- a/maskdyads
+++ b/maskdyads
@@ -11,7 +11,7 @@ Usage() {
     exit
 }
 
-[ "$1" = ""] && Usage
+[ "$1" = "" ] && Usage
 
 d=`$FSLDIR/bin/remove_ext $1`
 f=$2