1 files changed, 1 insertions, 0 deletions
diff --git a/pack.c b/pack.c
index 2ecb2d68d6..c4ee6dbb30 100644
--- a/pack.c
+++ b/pack.c
@@ -1017,6 +1017,7 @@ pack_pack(VALUE ary, VALUE fmt)
     if (associates) {
 	rb_str_associate(res, associates);
     }
+    OBJ_INFECT(res, fmt);
     return res;
 }