diff --git a/src/sync/runtime.go b/src/sync/runtime.go
index be16bcc8f7b15..a13d9f6cf1ee6 100644
--- a/src/sync/runtime.go
+++ b/src/sync/runtime.go
@@ -54,7 +54,7 @@ func init() {
 }
 
 // Active spinning runtime support.
-// runtime_canSpin returns true is spinning makes sense at the moment.
+// runtime_canSpin returns true if spinning makes sense at the moment.
 func runtime_canSpin(i int) bool
 
 // runtime_doSpin does active spinning.