diff --git a/prompt_fred_setup b/prompt_fred_setup
index c93394e..6bcaa62 100644
--- a/prompt_fred_setup
+++ b/prompt_fred_setup
@@ -1,6 +1,7 @@
 # -*-mode: sh-*-
 # My mess of various themes
 
+setopt PROMPT_SUBST #allows prompt substitutions
 if [[ $(locale charmap) != UTF-8 || "$TERM" == linux ]]
 then
   ERROR_CHAR=''