diff --git a/powerlevel9k.zsh-theme b/powerlevel9k.zsh-theme
index 473e17b0..9a1a9100 100755
--- a/powerlevel9k.zsh-theme
+++ b/powerlevel9k.zsh-theme
@@ -372,7 +372,7 @@ prompt_hdd_usage() {
   fi
 
   current_state='normal'
-  local message="$level% "
+  local message="${level}%"
 
   if [ $level -le $POWERLEVEL9K_HDD_USAGE_WARNING_LEVEL ]; then
     current_state='warning'