diff --git a/os/various/lwip_bindings/arch/cc.h b/os/various/lwip_bindings/arch/cc.h
index b94e6f4d8..0eb359c99 100644
--- a/os/various/lwip_bindings/arch/cc.h
+++ b/os/various/lwip_bindings/arch/cc.h
@@ -73,12 +73,4 @@ typedef uint32_t        mem_ptr_t;
 #define BYTE_ORDER LITTLE_ENDIAN
 #define LWIP_PROVIDE_ERRNO
 
-#define PACK_STRUCT_BEGIN
-#ifdef PACK_STRUCT_STRUCT
-#undef PACK_STRUCT_STRUCT
-#endif
-#define PACK_STRUCT_STRUCT __attribute__ ((__packed__))
-#define PACK_STRUCT_END
-#define PACK_STRUCT_FIELD(x) x
-
 #endif /* __CC_H__ */
diff --git a/readme.txt b/readme.txt
index d647c8a47..67b9f1d43 100644
--- a/readme.txt
+++ b/readme.txt
@@ -83,6 +83,8 @@
 *****************************************************************************
 
 *** 2.5.1 ***
+- FIX: Fixed superfluous pack #defines cause nasty warning (bug 3575662)
+  (backported to 2.4.3).
 - FIX: Fixed mac.c won't compile due to misplaced declarations (bug 3575657)
   (backported to 2.4.3).
 - FIX: Fixed STM32F4 ADC prescaler incorrectly initialized (bug 3575297)