diff --git a/lib/git.zsh b/lib/git.zsh
index 86f46ed5d..915575246 100644
--- a/lib/git.zsh
+++ b/lib/git.zsh
@@ -4,7 +4,7 @@ function git_prompt_info() {
   if [ -z $ref ]; then
     # check if in detached HEAD mode
     branch_name=$(git status -sb $(git_submodule_syntax) 2> /dev/null)
-    if [ $branch_name = "## HEAD (no branch)" ]; then
+    if [ "$branch_name" = "## HEAD (no branch)" ]; then
       # set tag name if found
       tag_name=$(git name-rev --name-only $(git --no-pager show --stat 2> /dev/null | head -n 1 | awk '{ print $2 }') 2> /dev/null)
       if [ -z $tag_name ]; then