1 files changed, 1 insertions, 1 deletions
diff --git a/struct.c b/struct.c
index efdf63f56e..819f1a8258 100644
--- a/struct.c
+++ b/struct.c
@@ -839,7 +839,7 @@ static VALUE
 struct_alloc(VALUE klass)
 {
     long n;
-    NEWOBJ_OF(st, struct RStruct, klass, T_STRUCT | (RGENGC_WB_PROTECTED_STRUCT ? FL_WB_PROTECTED : 0));
+    NEWOBJ_OF(st, struct RStruct, klass, T_STRUCT | (RGENGC_WB_PROTECTED_STRUCT ? FL_WB_PROTECTED : 0), sizeof(struct RStruct), 0);
 
     n = num_members(klass);