diff --git a/library/std/src/sync/once.rs b/library/std/src/sync/once.rs
index 1b17c31089ff2..8c46080e43b38 100644
--- a/library/std/src/sync/once.rs
+++ b/library/std/src/sync/once.rs
@@ -91,7 +91,7 @@ impl Once {
     /// return).
     ///
     /// If the given closure recursively invokes `call_once` on the same [`Once`]
-    /// instance the exact behavior is not specified, allowed outcomes are
+    /// instance, the exact behavior is not specified: allowed outcomes are
     /// a panic or a deadlock.
     ///
     /// # Examples