diff --git a/sv-disable b/sv-disable
index 33243c2..76d5c5b 100755
--- a/sv-disable
+++ b/sv-disable
@@ -12,7 +12,7 @@ if [ -z "$1" ];then
     show_help
     exit 1
 fi
-if [ -u "$SVDIR" ];then
+if [ -z "$SVDIR" ];then
     >&2 echo "Error: SVDIR not set"
     exit 1
 fi
diff --git a/sv-enable b/sv-enable
index c4dd6b4..c9a1c94 100755
--- a/sv-enable
+++ b/sv-enable
@@ -12,7 +12,7 @@ if [ -z "$1" ];then
     show_help
     exit 1
 fi
-if [ -u "$SVDIR" ];then
+if [ -z "$SVDIR" ];then
     >&2 echo "Error: SVDIR not set"
     exit 1
 fi