diff --git a/core/net/uip6.c b/core/net/uip6.c
index 942e0dfae..021cbf888 100644
--- a/core/net/uip6.c
+++ b/core/net/uip6.c
@@ -508,7 +508,7 @@ remove_ext_hdr(void)
   if(uip_ext_len > 0) {
     PRINTF("Cutting ext-header before processing (extlen: %d, uiplen: %d)\n",
 	   uip_ext_len, uip_len);
-    if(uip_len - UIP_IPH_LEN - uip_ext_len < 0) {
+    if(uip_len < UIP_IPH_LEN + uip_ext_len) {
       PRINTF("ERROR: uip_len too short compared to ext len\n");
       uip_ext_len = 0;
       uip_len = 0;