diff --git a/lib/nghttp2_helper.h b/lib/nghttp2_helper.h
index 979b64af..89631823 100644
--- a/lib/nghttp2_helper.h
+++ b/lib/nghttp2_helper.h
@@ -40,11 +40,8 @@
 
 #define lstreq(A, B, N) ((sizeof((A)) - 1) == (N) && memcmp((A), (B), (N)) == 0)
 
-#define nghttp2_struct_of(ptr, type, member)                                    \
-  ({                                                                            \
-    const typeof(((type *)0)->member) *nghttp2__mptr = (ptr);                   \
-    (type *)(void *)((char *)nghttp2__mptr - __builtin_offsetof(type, member)); \
-  })
+#define nghttp2_struct_of(ptr, type, member)                                   \
+  ((type *)(void *)((char *)(ptr) - offsetof(type, member)))
 
 /*
  * Copies 2 byte unsigned integer |n| in host byte order to |buf| in