diff --git a/src/test/objectstore/hybrid_allocator_test.cc b/src/test/objectstore/hybrid_allocator_test.cc
index c7ecfde021d..c17e6b73dd2 100755
--- a/src/test/objectstore/hybrid_allocator_test.cc
+++ b/src/test/objectstore/hybrid_allocator_test.cc
@@ -55,6 +55,29 @@ TEST(BitmapAllocator, claim_edge)
   }
 }
 
+TEST(BitmapAllocator, claim_bad_alloc_unit)
+{
+  uint64_t block_size = 0x10000;
+  uint64_t capacity = _4m;
+  BitmapAllocator ha(g_ceph_context, capacity, block_size,
+    "test_allocator");
+
+  // mark the first chunk free
+  ha.init_add_free(0, block_size);
+
+  // Then we simulate hybrid allocator behavior when someone is releasing
+  // extent starting at offset 0x14000. The master allocator will
+  // search for free extents adjusting the above offset on the left
+  // via claim_free_to_left() call.
+  // 
+  // Non-zero return means that master can do the merge which is wrong
+  // in this scenario and when occurred within hybrid allocator it will improperly
+  // mark extent 0x10000~0x4000 as free. Which in turn might result in data corruption.
+  //
+  auto r = ha.claim_free_to_left(block_size + 0x4000);
+  ASSERT_EQ(r, 0);
+}
+
 TEST(HybridAllocator, basic)
 {
   {