diff --git a/core/net/sicslowpan.c b/core/net/sicslowpan.c
index 1f1e0dfd0..dd546d465 100644
--- a/core/net/sicslowpan.c
+++ b/core/net/sicslowpan.c
@@ -32,7 +32,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: sicslowpan.c,v 1.39 2010/05/11 10:02:29 nifi Exp $
+ * $Id: sicslowpan.c,v 1.40 2010/05/24 10:07:34 joxe Exp $
  */
 /**
  * \file
@@ -157,8 +157,8 @@ void uip_log(char *msg);
 /** \name Pointers in the sicslowpan and uip buffer
  *  @{
  */
-#define SICSLOWPAN_IP_BUF   ((struct uip_ip_hdr *)&sicslowpan_buf[UIP_LLH_LEN])
-#define SICSLOWPAN_UDP_BUF ((struct uip_udp_hdr *)&sicslowpan_buf[UIP_LLIPH_LEN])
+#define SICSLOWPAN_IP_BUF   ((struct uip_ip_hdr *)&sicslowpan_buf.u8[UIP_LLH_LEN])
+#define SICSLOWPAN_UDP_BUF ((struct uip_udp_hdr *)&sicslowpan_buf.u8[UIP_LLIPH_LEN])
 
 #define UIP_IP_BUF          ((struct uip_ip_hdr *)&uip_buf[UIP_LLH_LEN])
 #define UIP_UDP_BUF          ((struct uip_udp_hdr *)&uip_buf[UIP_LLIPH_LEN])
@@ -221,9 +221,7 @@ static u16_t sicslowpan_len;
  * It has a fix size as we do not use dynamic memory allocation.
  */
 
-/* Allocate buffer as 32 bit to ensure that it is 32-bit aligned */
-static uint32_t uip_buf32[(UIP_BUFSIZE + 3) / 4];
-static uint8_t * const sicslowpan_buf = (uint8_t * const) uip_buf32;
+static uip_buf_t sicslowpan_buf;
 
 /** The total length of the IPv6 packet in the sicslowpan_buf. */
 
diff --git a/core/net/uip.c b/core/net/uip.c
index 69b57ad29..59e4d8fb4 100644
--- a/core/net/uip.c
+++ b/core/net/uip.c
@@ -41,7 +41,7 @@
  *
  * This file is part of the uIP TCP/IP stack.
  *
- * $Id: uip.c,v 1.27 2010/05/08 07:23:55 oliverschmidt Exp $
+ * $Id: uip.c,v 1.28 2010/05/24 10:07:34 joxe Exp $
  *
  */
 
@@ -126,13 +126,11 @@ const struct uip_eth_addr uip_ethaddr = {{UIP_ETHADDR0,
 struct uip_eth_addr uip_ethaddr = {{0,0,0,0,0,0}};
 #endif
 
+/* The packet buffer that contains incoming packets. */
 #ifdef UIP_CONF_PLAIN_BUFFER
 uint8_t uip_buf[UIP_BUFSIZE + 2];
 #else /* UIP_CONF_PLAIN_BUFFER */
-static uint32_t uip_buf32[(UIP_BUFSIZE + 3) / 4];
-uint8_t * const uip_buf = (uint8_t * const)uip_buf32; 
-                                 /* The packet buffer that contains
-				    incoming packets. */
+uip_buf_t uip_aligned_buf;
 #endif /* UIP_CONF_PLAIN_BUFFER */
 
 void *uip_appdata;               /* The uip_appdata pointer points to
diff --git a/core/net/uip.h b/core/net/uip.h
index 77b591386..0ea01c24f 100644
--- a/core/net/uip.h
+++ b/core/net/uip.h
@@ -47,7 +47,7 @@
  *
  * This file is part of the uIP TCP/IP stack.
  *
- * $Id: uip.h,v 1.32 2010/05/08 07:23:55 oliverschmidt Exp $
+ * $Id: uip.h,v 1.33 2010/05/24 10:07:34 joxe Exp $
  *
  */
 
@@ -476,10 +476,17 @@ void uip_reass_over(void);
  }
  \endcode
 */
+
+typedef union {
+  uint32_t u32[(UIP_BUFSIZE + 3) / 4];
+  uint8_t u8[UIP_BUFSIZE];
+} uip_buf_t;
+
 #ifdef UIP_CONF_PLAIN_BUFFER
 CCIF extern uint8_t uip_buf[UIP_BUFSIZE+2];
 #else /* UIP_CONF_PLAIN_BUFFER */
-CCIF extern uint8_t * const uip_buf;
+CCIF extern uip_buf_t uip_aligned_buf;
+#define uip_buf (uip_aligned_buf.u8)
 #endif /* UIP_CONF_PLAIN_BUFFER */
 
 
diff --git a/core/net/uip6.c b/core/net/uip6.c
index a8b5c6b22..9ad6a4320 100644
--- a/core/net/uip6.c
+++ b/core/net/uip6.c
@@ -41,7 +41,7 @@
  *
  * This file is part of the uIP TCP/IP stack.
  *
- * $Id: uip6.c,v 1.22 2010/05/07 20:45:16 oliverschmidt Exp $
+ * $Id: uip6.c,v 1.23 2010/05/24 10:07:34 joxe Exp $
  *
  */
 
@@ -170,11 +170,9 @@ u8_t uip_ext_opt_offset = 0;
  */
 /** Packet buffer for incoming and outgoing packets */
 #ifndef UIP_CONF_EXTERNAL_BUFFER
-static uint32_t uip_buf32[(UIP_BUFSIZE + 3) / 4];
+uip_buf_t uip_aligned_buf;
 #endif /* UIP_CONF_EXTERNAL_BUFFER */
 
-uint8_t * const uip_buf = (uint8_t * const) uip_buf32;
-
 /* The uip_appdata pointer points to application data. */
 void *uip_appdata;
 /* The uip_appdata pointer points to the application data which is to be sent*/