diff --git a/ps1.sh b/ps1.sh
index be7249a..c2294c8 100644
--- a/ps1.sh
+++ b/ps1.sh
@@ -1,12 +1,15 @@
 #!/usr/bin/env bash
-# ps1.sh - Bash PS1 with emoji + optional animation helpers
-# Source this file:  source /path/to/ps1.sh
-# Then enable:       ps1_on
-# Optional animate:  psanimate 0.5
-# Stop animation:    psanimate_stop
-# Disable:           ps1_off
 
-# Only for interactive bash
+# Must be sourced, not executed
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+  echo "Dette scriptet må kjøres med:"
+  echo "  source ps1.sh"
+  echo "eller:"
+  echo "  . ps1.sh"
+  exit 1
+fi
+
+# Only for interactive shells
 case "$-" in
   *i*) ;;
   *) return 0 ;;