diff --git a/include/my_global.h b/include/my_global.h
index 6970fa5a0b6..c350982fbb0 100644
--- a/include/my_global.h
+++ b/include/my_global.h
@@ -478,7 +478,7 @@ C_MODE_END
 #include <assert.h>
 
 /* an assert that works at compile-time. only for constant expression */
-#ifndef __GNUC__
+#ifdef _some_old_compiler_that_does_not_understand_the_construct_below_
 #define compile_time_assert(X)  do { } while(0)
 #else
 #define compile_time_assert(X)                                  \
diff --git a/include/waiting_threads.h b/include/waiting_threads.h
index 0df17a47c61..322b5972ec0 100644
--- a/include/waiting_threads.h
+++ b/include/waiting_threads.h
@@ -19,10 +19,10 @@
 #include <my_global.h>
 #include <my_sys.h>
 
-C_MODE_START
-
 #include <lf.h>
 
+C_MODE_START
+
 typedef struct st_wt_resource_id WT_RESOURCE_ID;
 
 typedef struct st_wt_resource_type {
@@ -30,10 +30,13 @@ typedef struct st_wt_resource_type {
   const void *(*make_key)(WT_RESOURCE_ID *id, uint *len);
 } WT_RESOURCE_TYPE;
 
+/* we want to compare this struct with memcmp, make it packed */
+#pragma pack(push,1)
 struct st_wt_resource_id {
-  WT_RESOURCE_TYPE *type;
   ulonglong value;
+  WT_RESOURCE_TYPE *type;
 };
+#pragma pack(pop)
 
 #define WT_WAIT_STATS  24
 #define WT_CYCLE_STATS 32
diff --git a/mysys/waiting_threads.c b/mysys/waiting_threads.c
index 255317ea4cc..489be6edbad 100644
--- a/mysys/waiting_threads.c
+++ b/mysys/waiting_threads.c
@@ -347,6 +347,8 @@ void wt_thd_destroy(WT_THD *thd)
 */
 int wt_resource_id_memcmp(void *a, void *b)
 {
+  /* assert that the structure is not padded with random bytes */
+  compile_time_assert(sizeof(WT_RESOURCE_ID)==sizeof(ulonglong)+sizeof(void*));
   return memcmp(a, b, sizeof(WT_RESOURCE_ID));
 }