diff --git a/isidore.sh b/isidore.sh
index c186f75..b15800a 100755
--- a/isidore.sh
+++ b/isidore.sh
@@ -55,7 +55,7 @@ function set_config_vars()
 
 	if [ -z "$ISIDORE_CONFIG_DIR" ]
 	then
-		if [ -z "$XDG_CONFIG_HOME" ]
+		if ! [ -z "$XDG_CONFIG_HOME" ]
 		then
 			ISIDORE_CONFIG_DIR="$XDG_CONFIG_HOME/isidore"
 		else