diff --git a/table/block_based/filter_policy.cc b/table/block_based/filter_policy.cc
index 6a458f72b..a4b93596e 100644
--- a/table/block_based/filter_policy.cc
+++ b/table/block_based/filter_policy.cc
@@ -338,7 +338,8 @@ FilterBitsReader* BloomFilterPolicy::GetFilterBitsReader(
     return new AlwaysFalseFilter();
   }
 
-  char raw_num_probes = contents.data()[len_with_meta - 5];
+  int8_t raw_num_probes =
+      static_cast<int8_t>(contents.data()[len_with_meta - 5]);
   // NB: *num_probes > 30 and < 128 probably have not been used, because of
   // BloomFilterPolicy::initialize, unless directly calling
   // FullFilterBitsBuilder as an API, but we are leaving those cases in