diff --git a/test/unordered/reserve_tests.cpp b/test/unordered/reserve_tests.cpp
index 578f0dfc..f0d83b91 100644
--- a/test/unordered/reserve_tests.cpp
+++ b/test/unordered/reserve_tests.cpp
@@ -1,4 +1,4 @@
-// Copyright 2021 Christian Mazakas.
+// Copyright 2021-2022 Christian Mazakas.
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
@@ -149,9 +149,11 @@ template <class UnorderedContainer> void rehash_tests()
     // no reallocations
     //
     std::size_t prev_allocations = num_allocations;
+    std::size_t prev_total_allocation = total_allocation;
 
     s.rehash(count);
     BOOST_TEST_EQ(num_allocations, prev_allocations);
+    BOOST_TEST_EQ(total_allocation, prev_total_allocation);
 
     // prove that when we rehash, exceeding the current bucket count, that we
     // properly deallocate the current bucket array and then reallocate the
@@ -171,8 +173,15 @@ template <class UnorderedContainer> void rehash_tests()
     // note, the test is vulnerable to cases where the next calculated bucket
     // count can exceed `prev_count + count`
     //
+    std::size_t const estimated_bucket_group_size =
+      3 * sizeof(void*) + sizeof(std::size_t);
+    std::size_t const estimated_bucket_groups =
+      s.bucket_count() / (sizeof(std::size_t) * 8);
+
     BOOST_TEST_LT(s.bucket_count(), prev_count + count);
-    BOOST_TEST_LT(total_allocation, (prev_count + count) * sizeof(void*));
+    BOOST_TEST_LE(total_allocation,
+      (prev_count + count) * sizeof(void*) +
+        estimated_bucket_group_size * estimated_bucket_groups);
   }
 
   BOOST_TEST_GT(num_allocations, 0u);