diff --git a/action.yml b/action.yml
index 3b001cf..b962c85 100644
--- a/action.yml
+++ b/action.yml
@@ -29,7 +29,7 @@ inputs:
       The regular expression pattern that PR labels will be tested on to decide whether the PR should be backported and where.
       The backport PR's base branch will be extracted from the pattern's required `base` named capturing group.
     # default: "^backport (?<base>([^ ]+))$"
-    default: "^backport (?<base>\d+\.\d+\.x)$"
+    default: '^backport (?<base>\d+\.\d+\.x)$'
   title_template:
     description: >
       Lodash template for the backport PR's title.