diff --git a/src/keyboard.c b/src/keyboard.c
index 142fa40afeb..4f2f2b816d0 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -7548,7 +7548,8 @@ On such systems, Emacs starts a subshell instead of suspending.")
   reset_sys_modes ();
   /* sys_suspend can get an error if it tries to fork a subshell
      and the system resources aren't available for that.  */
-  record_unwind_protect (init_sys_modes, 0);
+  record_unwind_protect ((Lisp_Object (*) P_ ((Lisp_Object))) init_sys_modes,
+			 0);
   stuff_buffered_input (stuffstring);
   if (cannot_suspend)
     sys_subshell ();