diff --git a/src/libostree/ostree-bloom.c b/src/libostree/ostree-bloom.c
index 6b42d97a78..8defb17673 100644
--- a/src/libostree/ostree-bloom.c
+++ b/src/libostree/ostree-bloom.c
@@ -273,11 +273,11 @@ ostree_bloom_maybe_contains (OstreeBloom   *bloom,
 
   for (i = 0; i < bloom->k; i++)
     {
-      gsize idx;
+      guint64 idx;
 
       idx = bloom->hash_func (element, i);
 
-      if (!ostree_bloom_get_bit (bloom, idx % (bloom->n_bytes * 8)))
+      if (!ostree_bloom_get_bit (bloom, (gsize) (idx % (bloom->n_bytes * 8))))
         return FALSE;  /* definitely not in the set */
     }
 
@@ -337,8 +337,8 @@ ostree_bloom_add_element (OstreeBloom   *bloom,
 
   for (i = 0; i < bloom->k; i++)
     {
-      gsize idx = bloom->hash_func (element, i);
-      ostree_bloom_set_bit (bloom, idx % (bloom->n_bytes * 8));
+      guint64 idx = bloom->hash_func (element, i);
+      ostree_bloom_set_bit (bloom, (gsize) (idx % (bloom->n_bytes * 8)));
     }
 }