diff --git a/src/basic/hash-funcs.c b/src/basic/hash-funcs.c
index d88df65a0d..608131a1c1 100644
--- a/src/basic/hash-funcs.c
+++ b/src/basic/hash-funcs.c
@@ -14,7 +14,7 @@ DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(string_hash_ops_free,
                                     char, string_hash_func, string_compare_func, free);
 DEFINE_HASH_OPS_FULL(string_hash_ops_free_free,
                      char, string_hash_func, string_compare_func, free,
-                     char, free);
+                     void, free);
 
 void path_hash_func(const char *q, struct siphash *state) {
         size_t n;