diff --git a/lib/omb-prompt-base.sh b/lib/omb-prompt-base.sh
index ccd7f86..069f328 100644
--- a/lib/omb-prompt-base.sh
+++ b/lib/omb-prompt-base.sh
@@ -170,7 +170,8 @@ function scm_prompt_info_common {
 function git_clean_branch {
   local unsafe_ref=$(command git symbolic-ref -q HEAD 2> /dev/null)
   local stripped_ref=${unsafe_ref##refs/heads/}
-  local clean_ref=${stripped_ref//[^a-zA-Z0-9\/_]/-}
+  local clean_ref=${stripped_ref//[\$\`\\]/-}
+  clean_ref=${clean_ref//[^[:print:]]/-} # strip escape sequences, etc.
   echo $clean_ref
 }