diff --git a/src/hashtag.c b/src/hashtag.c
index ba73e35..2e44e33 100644
--- a/src/hashtag.c
+++ b/src/hashtag.c
@@ -52,7 +52,7 @@ char* construct_hashtag(struct mstdnt_tag* hashtag, size_t* size)
     return tmpl_gen_hashtag(&data, size);
 }
 
-static char* construct_hashtag_voidwrap(void* passed, size_t index, int* res)
+static char* construct_hashtag_voidwrap(void* passed, size_t index, size_t* res)
 {
     return construct_hashtag((struct mstdnt_tag*)passed + index, res);
 }
diff --git a/src/scrobble.c b/src/scrobble.c
index 96d3e20..eb0aab1 100644
--- a/src/scrobble.c
+++ b/src/scrobble.c
@@ -42,7 +42,7 @@ char* construct_scrobble(struct mstdnt_scrobble* scrobble, size_t* size)
     return tmpl_gen_scrobble(&tdata, size);
 }
 
-static char* construct_scrobble_voidwrap(void* passed, size_t index, int* res)
+static char* construct_scrobble_voidwrap(void* passed, size_t index, size_t* res)
 {
     return construct_scrobble((struct mstdnt_scrobble*)passed + index, res);
 }