diff --git a/libports/include/lwip/lwipopts.h b/libports/include/lwip/lwipopts.h
index d1803c80b..8a743c334 100644
--- a/libports/include/lwip/lwipopts.h
+++ b/libports/include/lwip/lwipopts.h
@@ -54,12 +54,8 @@
 
 #define MEM_LIBC_MALLOC             1
 #define MEMP_MEM_MALLOC             1
-#ifdef __x86_64__
-#define MEM_ALIGNMENT               8
-#else
+/* MEM_ALIGNMENT > 4 e.g. for x86_64 are not supported, see Genode issue #817 */
 #define MEM_ALIGNMENT               4
-#endif
-#define ETH_PAD_SIZE                2
 
 #define DEFAULT_ACCEPTMBOX_SIZE   128
 #define TCPIP_MBOX_SIZE           128