diff --git a/include/ucore/iomux.h b/include/ucore/iomux.h
index f5604fb..414ce21 100644
--- a/include/ucore/iomux.h
+++ b/include/ucore/iomux.h
@@ -132,6 +132,11 @@ int iomux_update_events(struct IOMux *mux, struct IOMuxFD *fd, unsigned int what
  */
 struct UCTimers *iomux_get_timers(struct IOMux *mux);
 
+/** Given an UCTimers associated with an IOMux, return the associated IOMux.
+ * (the UCTimers must previously been obtained from iomux_get_timers directly,
+ * or indirectly by the UCTimers provieded in a timer callback handler.
+ */
+struct IOMux *iomux_from_timers(struct UCTimers *timers);
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/iomux_impl.c b/src/iomux_impl.c
index a1e52c2..bbb16bc 100644
--- a/src/iomux_impl.c
+++ b/src/iomux_impl.c
@@ -168,3 +168,8 @@ struct UCTimers *iomux_get_timers(struct IOMux *mux)
     return &mux->timers;
 }
 
+struct IOMux *iomux_from_timers(struct UCTimers *timers)
+{
+    return (struct IOMux*)timers; //timers is the 1. member of IOMux
+}
+
diff --git a/src/iomux_impl.h b/src/iomux_impl.h
index 794c738..ea51873 100644
--- a/src/iomux_impl.h
+++ b/src/iomux_impl.h
@@ -29,7 +29,7 @@ struct IOMuxOps {
 };
 
 struct IOMux {
-    /* TImer instance */
+    /* TImer instance - must be the 1. member*/
     struct UCTimers timers;
 
     /**
diff --git a/test/udp_heartbeat.c b/test/udp_heartbeat.c
index f33255f..3e73385 100644
--- a/test/udp_heartbeat.c
+++ b/test/udp_heartbeat.c
@@ -1,5 +1,6 @@
 #define DEBUG
 #include <getopt.h>
+#include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <time.h>
@@ -76,6 +77,7 @@ void peer_timer_cb(struct UCTimers *timers, struct UCTimer *timer)
     struct HBPeer *peer = UC_CONTAINER_OF(timer, struct HBPeer, timer);
     struct HBContext *ctx = timer->cookie_ptr;
     time_t now;
+    struct IOMux *mux;
 
     uc_timers_add(timers, timer, PEER_HB_MISS , 0);
     now = time(NULL);
@@ -85,6 +87,9 @@ void peer_timer_cb(struct UCTimers *timers, struct UCTimer *timer)
     }
 
     peer_send(ctx, peer);
+    //jsut a small test of iomux_from_timers
+    mux = iomux_from_timers(timers);
+    assert(mux == ctx->mux);
 }
 
 void peer_add_addr(struct HBContext *ctx, const struct sockaddr_in *addr)