diff --git a/src/pygit2/repository.c b/src/pygit2/repository.c
index f5f31d3..5d0fc84 100644
--- a/src/pygit2/repository.c
+++ b/src/pygit2/repository.c
@@ -162,12 +162,12 @@ Repository_contains(Repository *self, PyObject *value)
 }
 
 static int
-Repository_build_as_iter(git_oid *oid, PyObject *accum)
+Repository_build_as_iter(const git_oid *oid, void *accum)
 {
     int err;
     PyObject *oid_str = git_oid_to_py_str(oid);
 
-    err = PyList_Append(accum, oid_str);
+    err = PyList_Append((PyObject*)accum, oid_str);
     Py_DECREF(oid_str);
     return err;
 }
@@ -184,7 +184,7 @@ Repository_as_iter(Repository *self)
         Error_set(err);
         return -1;
     }
-    err = git_odb_foreach(odb, Repository_build_as_iter, accum);
+    err = git_odb_foreach(odb, Repository_build_as_iter, (void*)accum);
     if (err == GIT_EUSER) {
         git_odb_free(odb);
         return -1;