diff --git a/styler/.local/bin/styler b/styler/.local/bin/styler
index 912079c..813e779 100755
--- a/styler/.local/bin/styler
+++ b/styler/.local/bin/styler
@@ -120,6 +120,10 @@ switch_theme() {
 # call processors for all installed packages
 set_theme() {
   local theme="$1"
+  if [[ -z $theme ]]; then
+    printf "Theme application requires an argument.\n"
+    exit 1
+  fi
   local permanent="${2:-true}"
 
   local packages