diff --git a/CHANGELOG b/CHANGELOG
index bd71cc17..39177b8f 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -6,10 +6,14 @@ HISTORY
 
   ++ New features:
 
-  2016-07-xx: Dirk Ziegelmeier:
+  2016-07-27: Simon Goldschmidt
+  * opt.h, timeouts.h/.c: added LWIP_TIMERS_CUSTOM to override the default
+    implementation of timeouts
+
+  2016-07-xx: Dirk Ziegelmeier
   * Large overhaul of doxygen documentation
 
-  2016-04-05: Simon Goldschmidt:
+  2016-04-05: Simon Goldschmidt
   * timers.h/.c: prepare for overriding current timeout implementation: all
     stack-internal caclic timers are avaliable in the lwip_cyclic_timers array
 
diff --git a/src/core/timeouts.c b/src/core/timeouts.c
index 9411800e..6c692ccc 100644
--- a/src/core/timeouts.c
+++ b/src/core/timeouts.c
@@ -106,7 +106,7 @@ const struct lwip_cyclic_timer lwip_cyclic_timers[] = {
 #endif /* LWIP_IPV6 */
 };
 
-#if LWIP_TIMERS
+#if LWIP_TIMERS && LWIP_TIMERS_CUSTOM
 
 /** The one and only timeout list */
 static struct sys_timeo *next_timeout;
@@ -426,10 +426,10 @@ again:
 
 #endif /* NO_SYS */
 
-#else /* LWIP_TIMERS */
+#else /* LWIP_TIMERS && LWIP_TIMERS_CUSTOM */
 /* Satisfy the TCP code which calls this function */
 void
 tcp_timer_needed(void)
 {
 }
-#endif /* LWIP_TIMERS */
+#endif /* LWIP_TIMERS && LWIP_TIMERS_CUSTOM */
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 5134185d..98567ca4 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -73,11 +73,28 @@
 #endif
 
 /**
- * NO_SYS_NO_TIMERS==1: Drop support for sys_timeout when NO_SYS==1
- * Mainly for compatibility to old versions.
+ * LWIP_TIMERS==0: Drop support for sys_timeout and lwip-internal cyclic timers.
+ * (the array of lwip-internal cyclic timers is still provided)
  */
-#if !defined NO_SYS_NO_TIMERS || defined __DOXYGEN__
-#define NO_SYS_NO_TIMERS                0
+#ifndef LWIP_TIMERS
+#define LWIP_TIMERS                     1
+#endif
+
+/**
+ * LWIP_TIMERS_CUSTOM==1: Provide your own timer implementation.
+ * Function prototypes in timeouts.h and the array of lwip-internal cyclic timers
+ * are still included, but the implementation is not. The following functions
+ * will be required: sys_timeouts_init(), sys_timeout(), sys_untimeout(),
+ *                   sys_timeouts_mbox_fetch()
+ * (check NO_SYS_NO_TIMERS for compatibility to old versions)
+ */
+#if !defined LWIP_TIMERS_CUSTOM || defined __DOXYGEN__
+#ifdef NO_SYS_NO_TIMERS
+#define LWIP_TIMERS                     (!NO_SYS || (NO_SYS && !NO_SYS_NO_TIMERS))
+#else
+#define LWIP_TIMERS                     1
+#endif
+#define LWIP_TIMERS_CUSTOM              0
 #endif
 /**
  * @}
diff --git a/src/include/lwip/priv/memp_std.h b/src/include/lwip/priv/memp_std.h
index 59f436df..ee3e2537 100644
--- a/src/include/lwip/priv/memp_std.h
+++ b/src/include/lwip/priv/memp_std.h
@@ -91,9 +91,9 @@ 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 (!NO_SYS || (NO_SYS && !NO_SYS_NO_TIMERS)) /* LWIP_TIMERS */
+#if LWIP_TIMERS && !LWIP_TIMERS_CUSTOM
 LWIP_MEMPOOL(SYS_TIMEOUT,    MEMP_NUM_SYS_TIMEOUT,     sizeof(struct sys_timeo),      "SYS_TIMEOUT")
-#endif /* LWIP_TIMERS */
+#endif /* LWIP_TIMERS && !LWIP_TIMERS_CUSTOM */
 
 #if LWIP_DNS && LWIP_SOCKET
 LWIP_MEMPOOL(NETDB,          MEMP_NUM_NETDB,           NETDB_ELEM_SIZE,               "NETDB")
diff --git a/src/include/lwip/timeouts.h b/src/include/lwip/timeouts.h
index 253c0fe6..4988b151 100644
--- a/src/include/lwip/timeouts.h
+++ b/src/include/lwip/timeouts.h
@@ -39,15 +39,6 @@
 #define LWIP_HDR_TIMEOUTS_H
 
 #include "lwip/opt.h"
-
-/** Timers are not supported when NO_SYS==1 and NO_SYS_NO_TIMERS==1.
- * Timer support can be disabled when cyclic timers are implemented
- * differently (use lwip_cyclic_timers array)
- */
-#ifndef LWIP_TIMERS
-#define LWIP_TIMERS (!NO_SYS || (NO_SYS && !NO_SYS_NO_TIMERS))
-#endif
-
 #include "lwip/err.h"
 #if !NO_SYS
 #include "lwip/sys.h"