--- old/src/hotspot/share/services/memTracker.cpp	2018-07-30 10:18:19.250950213 -0400
+++ new/src/hotspot/share/services/memTracker.cpp	2018-07-30 10:18:19.107950456 -0400
@@ -32,6 +32,7 @@
 #include "services/memReporter.hpp"
 #include "services/mallocTracker.inline.hpp"
 #include "services/memTracker.hpp"
+#include "utilities/debug.hpp"
 #include "utilities/defaultStream.hpp"
 #include "utilities/vmError.hpp"
 
@@ -50,6 +51,9 @@
 
 
 NMT_TrackingLevel MemTracker::init_tracking_level() {
+  // memory type occupies a byte
+  STATIC_ASSERT(mt_number_of_types <= max_jubyte);
+
   NMT_TrackingLevel level = NMT_off;
   char buf[64];
   jio_snprintf(buf, sizeof(buf), "NMT_LEVEL_%d", os::current_process_id());