diff --git a/src/share/vm/services/memoryService.cpp b/src/share/vm/services/memoryService.cpp
index 0040f9d96fca0f146c912eed84d5182ff8b5cc80..75693dbcf69b2a3f997c5518376fbfd6b638113a 100644
--- a/src/share/vm/services/memoryService.cpp
+++ b/src/share/vm/services/memoryService.cpp
@@ -240,6 +240,7 @@ MemoryPool* MemoryService::add_cms_space(CompactibleFreeListSpace* space,
 void MemoryService::add_generation_memory_pool(Generation* gen,
                                                MemoryManager* major_mgr,
                                                MemoryManager* minor_mgr) {
+  guarantee(gen != NULL, "No generation for memory pool");
   Generation::Name kind = gen->kind();
   int index = _pools_list->length();