diff --git a/scripts/client-preexec.sh b/scripts/client-preexec.sh
index bea84df..662189f 100755
--- a/scripts/client-preexec.sh
+++ b/scripts/client-preexec.sh
@@ -2,7 +2,9 @@
 #
 # Execute *before* doing anything
 #
-if [[ "$(sha1sum discover-routes | cut -f1 -d' ')" == "246d9bbeded14ef58e5bc103af0f8c2e8b2e8cf2" ]]; then
-  echo "!!! Rewriting stale 'discover-routes' script"
-  cp discover-routes.aws.example discover-routes
+if [[ -f discover-routes ]]; then
+  if [[ "$(sha1sum discover-routes | cut -f1 -d' ')" == "246d9bbeded14ef58e5bc103af0f8c2e8b2e8cf2" ]]; then
+    echo "!!! Rewriting stale 'discover-routes' script"
+    cp discover-routes.aws.example discover-routes
+  fi
 fi