diff --git a/NEWS b/NEWS
index babea324fe8..a8428f0099e 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ PHP                                                                        NEWS
     (nielsdos)
   . Fixed bug GH-16630 (UAF in lexer with encoding translation and heredocs).
     (nielsdos)
+  . Fix is_zend_ptr() huge block comparison. (nielsdos)
 
 - Curl:
   . Fixed bug GH-16802 (open_basedir bypass using curl extension). (nielsdos)
diff --git a/Zend/zend_alloc.c b/Zend/zend_alloc.c
index 50f1bbbb69c..d531270d445 100644
--- a/Zend/zend_alloc.c
+++ b/Zend/zend_alloc.c
@@ -2471,8 +2471,8 @@ ZEND_API bool is_zend_ptr(const void *ptr)
 
 	zend_mm_huge_list *block = AG(mm_heap)->huge_list;
 	while (block) {
-		if (ptr >= (void*)block
-				&& ptr < (void*)((char*)block + block->size)) {
+		if (ptr >= block->ptr
+				&& ptr < (void*)((char*)block->ptr + block->size)) {
 			return 1;
 		}
 		block = block->next;