diff --git a/CHANGELOG b/CHANGELOG
index 6f282caee..07b65872e 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,9 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o Fixed a bug that could cause Nsock timers to fire too early. This
+  could happen for the timed probes in IPv6 OS detection, causing an
+  incorrect measurement of the TCP_ISR feature. [David Fifield]
+
 o [NSE] Added a stun library and the scripts stun-version and stun-info, which
   extract version information and the external NAT:ed address.
   [Patrik Karlsson]
diff --git a/nsock/src/nsock_timers.c b/nsock/src/nsock_timers.c
index 1d350ace1..254ce1dfc 100644
--- a/nsock/src/nsock_timers.c
+++ b/nsock/src/nsock_timers.c
@@ -57,6 +57,8 @@
 
 #include "nsock_internal.h"
 
+extern struct timeval nsock_tod;
+
 /* Send back an NSE_TYPE_TIMER after the number of milliseconds specified.  Of
  * course it can also return due to error, cancellation, etc. */
 nsock_event_id nsock_timer_create(nsock_pool ms_pool, nsock_ev_handler handler,
@@ -64,6 +66,8 @@ nsock_event_id nsock_timer_create(nsock_pool ms_pool, nsock_ev_handler handler,
   mspool *nsp = (mspool *)ms_pool;
   msevent *nse;
 
+  gettimeofday(&nsock_tod, NULL);
+
   nse = msevent_new(nsp, NSE_TYPE_TIMER, NULL, timeout_msecs, handler, userdata);
   assert(nse);