diff --git a/src/alloc.c b/src/alloc.c
index a4e97d7a8c3..c0c24c65737 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -6028,7 +6028,7 @@ Each entry has the form (NAME SIZE USED FREE), where:
 - FREE is the number of those objects that are not live but that Emacs
   keeps around for future allocations (maybe because it does not know how
   to return them to the OS).  */)
-  ()
+  (void)
 {
   struct gcstat gcst = gcstat;