diff --git a/autoenv.zsh b/autoenv.zsh
index f7e4f98..df90cc5 100644
--- a/autoenv.zsh
+++ b/autoenv.zsh
@@ -140,7 +140,7 @@ _autoenv_stack_entered_contains() {
 
 # Internal function for debug output. {{{
 _autoenv_debug() {
-  local msg=$1
+  local msg="$1"
   local level=${2:-1}
   if [[ $AUTOENV_DEBUG -lt $level ]]; then
     return