diff --git a/lualib-src/lua-bson.c b/lualib-src/lua-bson.c
index f2904852..9d20242a 100644
--- a/lualib-src/lua-bson.c
+++ b/lualib-src/lua-bson.c
@@ -1086,6 +1086,7 @@ lbinary(lua_State *L) {
 	luaL_addchar(&b, 0);
 	luaL_addchar(&b, BSON_BINARY);
 	luaL_addchar(&b, 0);	// sub type
+	lua_pushvalue(L,1);
 	luaL_addvalue(&b);
 	luaL_pushresult(&b);