diff --git a/Makefile.cc b/Chaos_Calmer.Makefile
similarity index 98%
rename from Makefile.cc
rename to Chaos_Calmer.Makefile
index 2d62a15..747cee4 100644
--- a/Makefile.cc
+++ b/Chaos_Calmer.Makefile
@@ -2,7 +2,7 @@ include $(TOPDIR)/rules.mk
 include $(INCLUDE_DIR)/kernel.mk
 
 PKG_NAME:=xmurp-ua
-PKG_RELEASE:=30
+PKG_RELEASE:=31
 
 include $(INCLUDE_DIR)/package.mk
 
diff --git a/Makefile b/Makefile
index 10c2021..18b3842 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ include $(TOPDIR)/rules.mk
 include $(INCLUDE_DIR)/kernel.mk
  
 PKG_NAME:=xmurp-ua
-PKG_RELEASE:=30
+PKG_RELEASE:=31
  
 include $(INCLUDE_DIR)/package.mk
 
diff --git a/compile.md b/compile.md
index 00f40e3..441a091 100644
--- a/compile.md
+++ b/compile.md
@@ -60,10 +60,10 @@ make package/xmurp-ua/compile V=sc ARCH=mips CROSS_COMPILE=/home/chn/Desktop/led
 
 #### 使用旧版 Makefile
 
-对于 Openwrt 15.05（Chaos Calmer），Makefile 的格式与最新版本不同。使用 `Makefile.cc` 代替 `Makefile` 再编译。
+对于 Openwrt 15.05（Chaos Calmer），Makefile 的格式与最新版本不同。使用 `Chaos_Calmer.Makefile` 代替 `Makefile` 再编译。
 
 ```bash
-cp package/xmurp-ua/Makefile.cc package/xmurp-ua/Makefile
+cp package/xmurp-ua/Chaos_Calmer.Makefile package/xmurp-ua/Makefile
 ```
 
 #### 失效的 host 命令
diff --git a/src/xmurp-ua.c b/src/xmurp-ua.c
index 7a0b31a..92e58f0 100644
--- a/src/xmurp-ua.c
+++ b/src/xmurp-ua.c
@@ -149,7 +149,7 @@ unsigned int hook_funcion(void *priv, struct sk_buff *skb, const struct nf_hook_
 
 	static u_int32_t n_ua_modified = 0, n_ua_modify_faild = 0, n_not_modifible = 0, n_mark_matched = 0;
 	static u_int32_t n_ua_modified_lastprint = 1;
-	static u_int8_t mark_matched = 0;
+	static u_int8_t mark_matched = 0, not_writable = 0;
 
 	register u_int8_t jump_to_next_function = 0, ret;
 
@@ -200,8 +200,13 @@ unsigned int hook_funcion(void *priv, struct sk_buff *skb, const struct nf_hook_
 		return NF_ACCEPT;
 
 	// 确保 skb 可以被修改，或者不可以被修改的话把它变得可修改
-	if(skb_ensure_writable(skb, (char*)data_end - (char*)skb -> data))
+	if(skb_ensure_writable(skb, (char*)data_end - (char*)skb -> data) || skb == 0 || skb -> data == 0)
 	{
+		if(!not_writable)
+		{
+			not_writable = 1;
+			printk("xmurp-ua: There is a package not wirtable. Please make sure the router has enough memory.\n");
+		}
 		n_not_modifible++;
 		n_ua_modify_faild++;
 		catch_next_frag = 0;