diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
index 5763a262ec..86948ee261 100644
--- a/src/libostree/ostree-repo.c
+++ b/src/libostree/ostree-repo.c
@@ -1558,8 +1558,10 @@ gboolean
 ostree_repo_is_writable (OstreeRepo *self,
                          GError **error)
 {
-  g_return_val_if_fail (self->inited, FALSE);
+  g_assert (self != NULL);
+  g_assert (self->inited);
 
+  g_assert (self->writable == (self->writable_error == NULL));
   if (error != NULL && self->writable_error != NULL)
     *error = g_error_copy (self->writable_error);
 
@@ -1595,7 +1597,8 @@ _ostree_repo_update_mtime (OstreeRepo        *self,
 GKeyFile *
 ostree_repo_get_config (OstreeRepo *self)
 {
-  g_return_val_if_fail (self->inited, NULL);
+  g_assert (self != NULL);
+  g_assert (self->inited);
 
   return self->config;
 }
@@ -1613,7 +1616,8 @@ ostree_repo_copy_config (OstreeRepo *self)
   char *data;
   gsize len;
 
-  g_return_val_if_fail (self->inited, NULL);
+  g_assert (self != NULL);
+  g_assert (self->inited);
 
   copy = g_key_file_new ();
   data = g_key_file_to_data (self->config, &len, NULL);
@@ -3812,7 +3816,8 @@ ostree_repo_equal (OstreeRepo *a,
 OstreeRepoMode
 ostree_repo_get_mode (OstreeRepo  *self)
 {
-  g_return_val_if_fail (self->inited, FALSE);
+  g_assert (self != NULL);
+  g_assert (self->inited);
 
   return self->mode;
 }