diff --git a/gc.c b/gc.c
index 0ba28ba67b..c1b06a76e7 100644
--- a/gc.c
+++ b/gc.c
@@ -12236,7 +12236,7 @@ objspace_xrealloc(rb_objspace_t *objspace, void *ptr, size_t new_size, size_t ol
 #endif
 
     old_size = objspace_malloc_size(objspace, ptr, old_size);
-    TRY_WITH_GC(new_size, mem = realloc(ptr, new_size));
+    TRY_WITH_GC(new_size, mem = RB_GNUC_EXTENSION_BLOCK(realloc(ptr, new_size)));
     new_size = objspace_malloc_size(objspace, mem, new_size);
 
 #if CALC_EXACT_MALLOC_SIZE