diff --git a/home-manager/home-manager b/home-manager/home-manager
index 3671f08b3..5c736dc52 100644
--- a/home-manager/home-manager
+++ b/home-manager/home-manager
@@ -102,7 +102,7 @@ function setHomeManagerNixPath() {
     if [[ -n "$path" ]] ; then
         if [[ -e "$path/flake.nix" ]] ; then
             # Set FLAKE_ARG if not set by --flake already
-            FLAKE_ARG=${FLAKE_ARG:-$path}
+            : "${FLAKE_ARG:=$path}"
         fi
         if [[ -e "$path" || "$path" =~ ^https?:// ]] ; then
             EXTRA_NIX_PATH+=("home-manager=$path")