diff --git a/winsup/cygwin/resource.cc b/winsup/cygwin/resource.cc
index 9a3cc21b8..46d74b984 100644
--- a/winsup/cygwin/resource.cc
+++ b/winsup/cygwin/resource.cc
@@ -147,6 +147,8 @@ __get_rlimit_stack (struct rlimit *rlp)
   rlimit_stack_guard.release ();
 }
 
+/* Interface to stack limit called from pthread_create and
+   pthread_attr_getstacksize. */
 size_t
 get_rlimit_stack (void)
 {