diff --git a/gitprompt.fish b/gitprompt.fish
index 3d60d02..b55a272 100644
--- a/gitprompt.fish
+++ b/gitprompt.fish
@@ -1,5 +1,5 @@
-if set -q $__GIT_PROMPT_DIR
-  set __GIT_PROMPT_DIR ~/.bash
+if not set -q __GIT_PROMPT_DIR
+    set __GIT_PROMPT_DIR ~/.bash
 end
 
 # Colors