diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index 37dc401ed0098..45308c4b3e9c5 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -1953,6 +1953,7 @@ impl str {
     ///
     /// ```
     /// assert_eq!("cfg".rsplit_once('='), None);
+    /// assert_eq!("cfg=".rsplit_once('='), Some(("cfg", "")));
     /// assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
     /// assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));
     /// ```