diff --git a/themes/giddie/prompt_giddie_setup b/themes/giddie/prompt_giddie_setup
index c3d3d4e7..74cce097 100644
--- a/themes/giddie/prompt_giddie_setup
+++ b/themes/giddie/prompt_giddie_setup
@@ -24,7 +24,7 @@ function prompt_giddie_precmd {
 
   # Choose prompt symbol based on whether on not we're in a repository.
   { git branch 2>&1 } >/dev/null
-  if [[ $? == 0 ]]; then
+  if (( $? == 0 )); then
     prompt_symbol='±'
   else
     prompt_symbol=')'