diff --git a/CHANGELOG b/CHANGELOG
index 40f13a1a..b3217826 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -564,6 +564,10 @@ HISTORY
 
   ++ Bug fixes:
 
+  2008-01-09 Jonathan Larmour
+  * opt.h, ip.c: Rename IP_OPTIONS define to IP_OPTIONS_ALLOWED to avoid
+  conflict with Linux system headers.
+
   2008-01-06 Jonathan Larmour
   * dhcp.c: fix bug #19927: "DHCP NACK problem" by clearing any existing set IP
   address entirely on receiving a DHCPNAK, and restarting discovery.
diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index c27eae0a..4b145309 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -357,7 +357,7 @@ ip_input(struct pbuf *p, struct netif *inp)
 #endif /* IP_REASSEMBLY */
   }
 
-#if IP_OPTIONS == 0 /* no support for IP options in the IP header? */
+#if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */
 
 #if LWIP_IGMP
   /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
@@ -365,7 +365,7 @@ ip_input(struct pbuf *p, struct netif *inp)
 #else
   if (iphdrlen > IP_HLEN) {
 #endif /* LWIP_IGMP */
-    LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS == 0).\n"));
+    LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
     pbuf_free(p);
     IP_STATS_INC(ip.opterr);
     IP_STATS_INC(ip.drop);
@@ -373,7 +373,7 @@ ip_input(struct pbuf *p, struct netif *inp)
     snmp_inc_ipinunknownprotos();
     return ERR_OK;
   }
-#endif /* IP_OPTIONS == 0 */
+#endif /* IP_OPTIONS_ALLOWED == 0 */
 
   /* send to upper layers */
   LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 461e6f35..a34cc27b 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -342,12 +342,12 @@
 #endif
 
 /**
- * IP_OPTIONS: Defines the behavior for IP options.
- *      IP_OPTIONS==0: All packets with IP options are dropped.
- *      IP_OPTIONS==1: IP options are allowed (but not parsed).
+ * IP_OPTIONS_ALLOWED: Defines the behavior for IP options.
+ *      IP_OPTIONS_ALLOWED==0: All packets with IP options are dropped.
+ *      IP_OPTIONS_ALLOWED==1: IP options are allowed (but not parsed).
  */
-#ifndef IP_OPTIONS
-#define IP_OPTIONS                      1
+#ifndef IP_OPTIONS_ALLOWED
+#define IP_OPTIONS_ALLOWED              1
 #endif
 
 /**