diff --git a/sit b/sit
index 88c346e..e6fe48f 100755
--- a/sit
+++ b/sit
@@ -72,7 +72,7 @@ case ${COMPILER} in
 esac
 
 # make the compiler variables CC, CXX, FC and F77 available
-if [ ! -z $COMPILER_OPTS ] ; then  
+if [ ! -z "$COMPILER_OPTS" ] ; then  
     export ${COMPILER_OPTS}
 fi