diff --git a/module/icp/algs/modes/gcm.c b/module/icp/algs/modes/gcm.c
index e666b45b5f..ee2100b7f4 100644
--- a/module/icp/algs/modes/gcm.c
+++ b/module/icp/algs/modes/gcm.c
@@ -806,7 +806,7 @@ static gcm_impl_ops_t *gcm_supp_impl[ARRAY_SIZE(gcm_all_impl)];
  * fallback to the fastest generic implementation.
  */
 const gcm_impl_ops_t *
-gcm_impl_get_ops()
+gcm_impl_get_ops(void)
 {
 	if (!kfpu_allowed())
 		return (&gcm_generic_impl);
diff --git a/module/os/linux/spl/spl-kmem-cache.c b/module/os/linux/spl/spl-kmem-cache.c
index bb2b568806..33aaad653d 100644
--- a/module/os/linux/spl/spl-kmem-cache.c
+++ b/module/os/linux/spl/spl-kmem-cache.c
@@ -1420,7 +1420,7 @@ EXPORT_SYMBOL(spl_kmem_cache_reap_now);
  * it should do no harm.
  */
 int
-spl_kmem_cache_reap_active()
+spl_kmem_cache_reap_active(void)
 {
 	return (0);
 }
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index 8892c2d5ac..9a273b010f 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -3947,7 +3947,7 @@ dmu_buf_get_user(dmu_buf_t *db_fake)
 }
 
 void
-dmu_buf_user_evict_wait()
+dmu_buf_user_evict_wait(void)
 {
 	taskq_wait(dbu_evict_taskq);
 }