diff --git a/src/_zkapauthorizer/storage_common.py b/src/_zkapauthorizer/storage_common.py
index 9af2a922fda5ce161a02294438842a3f3f27e5c3..885529dedc094d0037ba9a03fddd893384d4ee11 100644
--- a/src/_zkapauthorizer/storage_common.py
+++ b/src/_zkapauthorizer/storage_common.py
@@ -166,7 +166,7 @@ def required_passes(bytes_per_pass, share_sizes):
             ),
         )
     result, b = divmod(sum(share_sizes, 0), bytes_per_pass)
-    if b:
+    if b > 0:
         result += 1
 
     # print("required_passes({}, {}) == {}".format(bytes_per_pass, share_sizes, result))