https://bugs.gentoo.org/944428#c2

--- a/src/common/hmap.c
+++ b/src/common/hmap.c
@@ -363,7 +363,7 @@ hmap_iterator(HMap *map, HMapIterator *it)
  * function. But no other entry.
  */
 void
-hmap_foreach_value(HMap *map, void (*iterator)())
+hmap_foreach_value(HMap *map, void (*iterator)(void*))
 {
     uint32_t c;
 
@@ -378,7 +378,7 @@ hmap_foreach_value(HMap *map, void (*iterator)())
 }
 
 void
-hmap_foreach_key(HMap *map, void (*iterator)())
+hmap_foreach_key(HMap *map, void (*iterator)(void*))
 {
     uint32_t c;
 
--- a/src/common/hmap.h
+++ b/src/common/hmap.h
@@ -50,8 +50,8 @@ void *hmap_put(HMap *map, void *key, void *value);
 bool hmap_contains_key(HMap *map, const void *key);
 void *hmap_remove(HMap *map, const void *key);
 void hmap_iterator(HMap *map, HMapIterator *it);
-void hmap_foreach_key(HMap *map, void (*iterator)());
-void hmap_foreach_value(HMap *map, void (*iterator)());
+void hmap_foreach_key(HMap *map, void (*iterator)(void*));
+void hmap_foreach_value(HMap *map, void (*iterator)(void*));
 void hmap_clear(HMap *map);
 size_t hmap_size(HMap *map);
 void hmap_set_hash_fn(HMap *map, hash_fn_t hash);
--- a/src/common/llist.c
+++ b/src/common/llist.c
@@ -445,7 +445,7 @@ llist_is_empty(LList *list)
 }
 
 void
-llist_iterate(LList *list, void (*iterator_func)())
+llist_iterate(LList *list, void (*iterator_func)(void*))
 {
 	LNode *entry;
 	for (entry = list->first; entry != NULL; entry = entry->next)
--- a/src/common/llist.h
+++ b/src/common/llist.h
@@ -68,7 +68,7 @@ LList *llist_clone(LList *list);
 void **llist_to_array(LList *list);
 void **llist_to_null_terminated_array(LList *list);
 
-void llist_iterate(LList *list, void (*iterator_func)());
+void llist_iterate(LList *list, void (*iterator_func)(void*));
 void llist_iterator(LList *list, LListIterator *it);
 
 void llist_reverse(LList *list);
--- a/src/common/tmap.c
+++ b/src/common/tmap.c
@@ -507,7 +507,7 @@ predecessor(TMapNode *node)
 #endif
 
 static void
-tmap_foreach_nodes_key(TMapNode *node, void (*iterator)())
+tmap_foreach_nodes_key(TMapNode *node, void (*iterator)(void*))
 {
     if (node->left != &nil)
     	tmap_foreach_nodes_key(node->left, iterator);
@@ -517,7 +517,7 @@ tmap_foreach_nodes_key(TMapNode *node, void (*iterator)())
 }
 
 static void
-tmap_foreach_nodes_value(TMapNode *node, void (*iterator)())
+tmap_foreach_nodes_value(TMapNode *node, void (*iterator)(void*))
 {
     if (node->left != &nil)
     	tmap_foreach_nodes_value(node->left, iterator);
@@ -527,14 +527,14 @@ tmap_foreach_nodes_value(TMapNode *node, void (*iterator)())
 }
 
 void
-tmap_foreach_key(TMap *map, void (*iterator)())
+tmap_foreach_key(TMap *map, void (*iterator)(void*))
 {
     if (map->root != &nil)
 	tmap_foreach_nodes_key(map->root, iterator);
 }
 
 void
-tmap_foreach_value(TMap *map, void (*iterator)())
+tmap_foreach_value(TMap *map, void (*iterator)(void*))
 {
     if (map->root != &nil)
 	tmap_foreach_nodes_value(map->root, iterator);
--- a/src/common/tmap.h
+++ b/src/common/tmap.h
@@ -51,8 +51,8 @@ void *tmap_remove(TMap *map, const void *key);
 void tmap_iterator(TMap *map, TMapIterator *it); /* value iterator */
 bool tmap_iterator_partial(TMap *map, TMapIterator *it, const void *match, comparison_fn_t comparator);
 void tmap_clear(TMap *map);
-void tmap_foreach_key(TMap *map, void (*iterator)());
-void tmap_foreach_value(TMap *map, void (*iterator)());
+void tmap_foreach_key(TMap *map, void (*iterator)(void*));
+void tmap_foreach_value(TMap *map, void (*iterator)(void*));
 
 #ifdef ENABLE_TMAP_TESTING
 #include <stdio.h>
--- a/src/list.c
+++ b/src/list.c
@@ -166,14 +166,14 @@ import_command(char **args)
     hmap_free(map_files);
     if (ferror(fh)) {
         warn(_("%s: cannot read from file: %s\n"), quotearg(args[1]), errstr);
-        llist_iterate(new_files, free_file_spec);
+        llist_iterate(new_files, (void(*)(void *))free_file_spec);
         llist_free(new_files);
         fclose(fh);
         return;
     }
     fclose(fh);
 
-    llist_iterate(work_files, free_file_spec);
+    llist_iterate(work_files, (void(*)(void *))free_file_spec);
     llist_free(work_files);
     work_files = new_files;
 }
@@ -370,7 +370,7 @@ list_files(char **args)
         free_plan(plan);
         plan = NULL;
     }
-    llist_iterate(work_files, free_file_spec);
+    llist_iterate(work_files, (void(*)(void *))free_file_spec);
     llist_clear(work_files);
 
     if (!process_ls_output(firstdir, work_files, ls_fd)) {
--- a/src/qcmd.c
+++ b/src/qcmd.c
@@ -263,7 +263,7 @@ main(int argc, char **argv)
 	free_plan(plan);
 
     /*dump_spec_list(work_files);*/
-    llist_iterate(work_files, free_file_spec);
+    llist_iterate(work_files, (void(*)(void *))free_file_spec);
     llist_free(work_files);
     free(all_options);
     free(editor_program);