diff --git a/CHANGELOG b/CHANGELOG
index 78a7fa89..f36a1b1b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -225,6 +225,10 @@ HISTORY
 
   ++ Bugfixes:
 
+  2010-06-24: Simon Goldschmidt
+  * init.c, timers.c/.h, opt.h, memp_std.h: From patch #7221: added flag
+    NO_SYS_NO_TIMERS to drop timer support for NO_SYS==1 for easier upgrading
+
   2010-06-24: Simon Goldschmidt
   * api(_lib).c/.h, api_msg.c/.h, sockets.c/.h: Fixed bug #10088: Correctly
     implemented shutdown at socket level.
diff --git a/src/core/init.c b/src/core/init.c
index 5763f104..949934ae 100644
--- a/src/core/init.c
+++ b/src/core/init.c
@@ -145,7 +145,7 @@
   #error "One and exactly one of LWIP_EVENT_API and LWIP_CALLBACK_API has to be enabled in your lwipopts.h"
 #endif
 /* There must be sufficient timeouts, taking into account requirements of the subsystems. */
-#if (MEMP_NUM_SYS_TIMEOUT < (LWIP_TCP + IP_REASSEMBLY + LWIP_ARP + (2*LWIP_DHCP) + LWIP_AUTOIP + LWIP_IGMP + LWIP_DNS + PPP_SUPPORT))
+#if LWIP_TIMERS && (MEMP_NUM_SYS_TIMEOUT < (LWIP_TCP + IP_REASSEMBLY + LWIP_ARP + (2*LWIP_DHCP) + LWIP_AUTOIP + LWIP_IGMP + LWIP_DNS + PPP_SUPPORT))
   #error "MEMP_NUM_SYS_TIMEOUT is too low to accomodate all required timeouts"
 #endif
 #if (IP_REASSEMBLY && (MEMP_NUM_REASSDATA > IP_REASS_MAX_PBUFS))
@@ -261,7 +261,9 @@ lwip_init(void)
 
   /* Modules initialization */
   stats_init();
+#if !NO_SYS
   sys_init();
+#endif /* !NO_SYS */
   mem_init();
   memp_init();
   pbuf_init();
@@ -295,5 +297,7 @@ lwip_init(void)
   dns_init();
 #endif /* LWIP_DNS */
 
+#if LWIP_TIMERS
   sys_timeouts_init();
+#endif /* LWIP_TIMERS */
 }
diff --git a/src/core/timers.c b/src/core/timers.c
index 0dba9272..a377b668 100644
--- a/src/core/timers.c
+++ b/src/core/timers.c
@@ -42,6 +42,9 @@
 #include "lwip/opt.h"
 
 #include "lwip/timers.h"
+
+#if LWIP_TIMERS
+
 #include "lwip/def.h"
 #include "lwip/memp.h"
 #include "lwip/tcpip.h"
@@ -485,3 +488,11 @@ sys_timeouts_mbox_fetch(sys_mbox_t *mbox, void **msg)
 }
 
 #endif /* NO_SYS */
+
+#else /* LWIP_TIMERS */
+/* Satisfy the TCP code which calls this function */
+void
+tcp_timer_needed(void)
+{
+}
+#endif /* LWIP_TIMERS */
diff --git a/src/include/lwip/memp_std.h b/src/include/lwip/memp_std.h
index 15d27823..550809ae 100644
--- a/src/include/lwip/memp_std.h
+++ b/src/include/lwip/memp_std.h
@@ -71,7 +71,9 @@ LWIP_MEMPOOL(ARP_QUEUE,      MEMP_NUM_ARP_QUEUE,       sizeof(struct etharp_q_en
 LWIP_MEMPOOL(IGMP_GROUP,     MEMP_NUM_IGMP_GROUP,      sizeof(struct igmp_group),     "IGMP_GROUP")
 #endif /* LWIP_IGMP */
 
+#if LWIP_TIMERS
 LWIP_MEMPOOL(SYS_TIMEOUT,    MEMP_NUM_SYS_TIMEOUT,     sizeof(struct sys_timeo),      "SYS_TIMEOUT")
+#endif /* LWIP_TIMERS */
 
 #if LWIP_SNMP
 LWIP_MEMPOOL(SNMP_ROOTNODE,  MEMP_NUM_SNMP_ROOTNODE,   sizeof(struct mib_list_rootnode), "SNMP_ROOTNODE")
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 968713e9..c5e3967e 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -68,6 +68,14 @@
 #define NO_SYS                          0
 #endif
 
+/**
+ * NO_SYS_NO_TIMERS==1: Drop support for sys_timeout when NO_SYS==1
+ * Mainly for compatibility to old versions.
+ */
+#ifndef NO_SYS_NO_TIMERS
+#define NO_SYS_NO_TIMERS                0
+#endif
+
 /**
  * MEMCPY: override this if you have a faster implementation at hand than the
  * one included in your C library
diff --git a/src/include/lwip/timers.h b/src/include/lwip/timers.h
index c680b24c..b0195ded 100644
--- a/src/include/lwip/timers.h
+++ b/src/include/lwip/timers.h
@@ -35,6 +35,11 @@
 
 #include "lwip/opt.h"
 
+/* Timers are not supported when NO_SYS==1 and NO_SYS_NO_TIMERS==1 */
+#define LWIP_TIMERS (!NO_SYS || (NO_SYS && !NO_SYS_NO_TIMERS))
+
+#if LWIP_TIMERS
+
 #include "lwip/err.h"
 #include "lwip/sys.h"
 
@@ -89,4 +94,5 @@ void sys_timeouts_mbox_fetch(sys_mbox_t *mbox, void **msg);
 }
 #endif
 
+#endif /* LWIP_TIMERS */
 #endif /* __LWIP_TIMERS_H__ */