diff --git a/configure/CONFIG b/configure/CONFIG
index 17440a39e..580b58767 100644
--- a/configure/CONFIG
+++ b/configure/CONFIG
@@ -73,17 +73,17 @@ ifdef T_A
   #
   -include $(CONFIG)/os/CONFIG.$(EPICS_HOST_ARCH).$(T_A)
 
+  #  Site specific target and host-target definitions and overrides
+  #
+  -include $(CONFIG)/os/CONFIG_SITE.Common.$(T_A)
+  -include $(CONFIG)/os/CONFIG_SITE.$(EPICS_HOST_ARCH).$(T_A)
+
   #  RELEASE file specific definitions
   #
   ifneq ($(CONFIG),$(TOP)/configure)
     -include $(CONFIG)/CONFIG_APP_INCLUDE
   endif
 
-  #  Site specific target and host-target definitions
-  #
-  -include $(CONFIG)/os/CONFIG_SITE.Common.$(T_A)
-  -include $(CONFIG)/os/CONFIG_SITE.$(EPICS_HOST_ARCH).$(T_A)
-
 endif # ifdef T_A
 
 
diff --git a/documentation/RELEASE_NOTES.html b/documentation/RELEASE_NOTES.html
index 7c5ade339..111c604d3 100644
--- a/documentation/RELEASE_NOTES.html
+++ b/documentation/RELEASE_NOTES.html
@@ -597,6 +597,17 @@ tells git to ignore all configure/*.local files.</p>
 
 <!-- Insert inherited items immediately below here ... -->
 
+<h3>Extend maximum Posix epicsEventWaitWithTimeout() delay</h3>
+
+<p>The Posix implementation of epicsEventWaitWithTimeout() was limiting the
+timeout delay to at most 60 minutes (3600.0 seconds). This has been changed to
+10 years; significantly longer maximum delays cause problems on systems where
+<tt>time_t</tt> is still a signed 32-bit integer so cannot represent absolute
+time-stamps after 2038-01-19. Our assumption is that such 32-bit systems will
+have been retired before the year 2028, but some additional tests have been
+added to the epicsTimeTest program to detect and fail if this assumption is
+violated.</p>
+
 <h3>New test-related make targets</h3>
 
 <p>This release adds several new make targets intended for use by developers
diff --git a/src/libCom/fdmgr/fdManager.cpp b/src/libCom/fdmgr/fdManager.cpp
index ff5022d81..00f4d4a87 100644
--- a/src/libCom/fdmgr/fdManager.cpp
+++ b/src/libCom/fdmgr/fdManager.cpp
@@ -113,7 +113,7 @@ epicsShareFunc void fdManager::process (double delay)
 
     if ( ioPending ) {
         struct timeval tv;
-        tv.tv_sec = static_cast<long> ( minDelay );
+        tv.tv_sec = static_cast<time_t> ( minDelay );
         tv.tv_usec = static_cast<long> ( (minDelay-tv.tv_sec) * uSecPerSec );
 
         fd_set * pReadSet = & this->fdSetsPtr[fdrRead];
diff --git a/src/libCom/osi/os/Darwin/osdTime.cpp b/src/libCom/osi/os/Darwin/osdTime.cpp
index c4a7e838c..72b3dc874 100644
--- a/src/libCom/osi/os/Darwin/osdTime.cpp
+++ b/src/libCom/osi/os/Darwin/osdTime.cpp
@@ -68,14 +68,14 @@ convertDoubleToWakeTime(double timeout, struct timespec *wakeTime)
     mach_timespec_t now;
     struct timespec wait;
 
+    if (timeout < 0.0)
+        timeout = 0.0;
+    else if (timeout > 60 * 60 * 24 * 3652.5)
+        timeout = 60 * 60 * 24 * 3652.5;    /* 10 years */
+
     clock_get_time(host_clock, &now);
 
-    if (timeout<0.0)
-        timeout = 0.0;
-    else if(timeout>3600.0)
-        timeout = 3600.0;
-
-    wait.tv_sec  = static_cast< long >(timeout);
+    wait.tv_sec  = static_cast< time_t >(timeout);
     wait.tv_nsec = static_cast< long >((timeout - (double)wait.tv_sec) * 1e9);
 
     wakeTime->tv_sec  = now.tv_sec + wait.tv_sec;
diff --git a/src/libCom/osi/os/posix/osdTime.cpp b/src/libCom/osi/os/posix/osdTime.cpp
index 2d98cf3ae..d5fb05a1c 100644
--- a/src/libCom/osi/os/posix/osdTime.cpp
+++ b/src/libCom/osi/os/posix/osdTime.cpp
@@ -88,30 +88,35 @@ int epicsTime_localtime ( const time_t *clock,
 extern "C" epicsShareFunc void
     convertDoubleToWakeTime(double timeout,struct timespec *wakeTime)
 {
-    struct timespec wait;
+    struct timespec now, wait;
     int status;
 
-    if(timeout<0.0) timeout = 0.0;
-    else if(timeout>3600.0) timeout = 3600.0;
+    if (timeout < 0.0)
+        timeout = 0.0;
+    else if (timeout > 60 * 60 * 24 * 3652.5)
+        timeout = 60 * 60 * 24 * 3652.5;    /* 10 years */
+
 #ifdef CLOCK_REALTIME
-    status = clock_gettime(CLOCK_REALTIME, wakeTime);
+    status = clock_gettime(CLOCK_REALTIME, &now);
 #else
     {
         struct timeval tv;
         struct timezone tz;
         status = gettimeofday(&tv, &tz);
-        wakeTime->tv_sec = tv.tv_sec;
-        wakeTime->tv_nsec = tv.tv_usec * 1000;
+        now.tv_sec = tv.tv_sec;
+        now.tv_nsec = tv.tv_usec * 1000;
     }
 #endif
     if (status) {
         perror("convertDoubleToWakeTime");
         cantProceed("convertDoubleToWakeTime");
     }
-    wait.tv_sec  = static_cast< long >(timeout);
+
+    wait.tv_sec  = static_cast< time_t >(timeout);
     wait.tv_nsec = static_cast< long >((timeout - (double)wait.tv_sec) * 1e9);
-    wakeTime->tv_sec  += wait.tv_sec;
-    wakeTime->tv_nsec += wait.tv_nsec;
+
+    wakeTime->tv_sec  = now.tv_sec + wait.tv_sec;
+    wakeTime->tv_nsec = now.tv_nsec + wait.tv_nsec;
     if (wakeTime->tv_nsec >= 1000000000L) {
         wakeTime->tv_nsec -= 1000000000L;
         ++wakeTime->tv_sec;
diff --git a/src/libCom/test/epicsTimeTest.cpp b/src/libCom/test/epicsTimeTest.cpp
index ec5da4c78..55ad43cdd 100644
--- a/src/libCom/test/epicsTimeTest.cpp
+++ b/src/libCom/test/epicsTimeTest.cpp
@@ -43,7 +43,7 @@ MAIN(epicsTimeTest)
     const int wasteTime = 100000;
     const int nTimes = 10;
 
-    testPlan(15 + nTimes * 19);
+    testPlan(17 + nTimes * 19);
 
     try {
         const epicsTimeStamp epochTS = {0, 0};
@@ -211,5 +211,35 @@ MAIN(epicsTimeTest)
         testOk1(beginTS + diff == now);
     }
 
+    epicsTime ten_years_hence;
+    try {
+        now = epicsTime::getCurrent();
+        ten_years_hence = now + 60 * 60 * 24 * 3652.5;
+        testPass("epicsTime can represent 10 years hence");
+    }
+    catch ( ... ) {
+        testFail("epicsTime exception for value 10 years hence");
+    }
+
+    try {
+        /* This test exists because in libCom/osi/os/posix/osdTime.cpp
+         * the convertDoubleToWakeTime() routine limits the timeout delay
+         * to 10 years. libCom/timer/timerQueue.cpp returns DBL_MAX for
+         * queues with no timers present, and convertDoubleToWakeTime()
+         * has to return an absolute Posix timestamp. On 2028-01-19 any
+         * systems that still implement time_t as a signed 32-bit integer
+         * will be unable to represent that timestamp, so this will fail.
+         */
+        time_t_wrapper os_time_t = ten_years_hence;
+        epicsTime then = os_time_t; // No fractional seconds
+        double delta = ten_years_hence - then;
+
+        testOk(delta >= 0 && delta < 1.0,
+            "OS time_t can represent 10 years hence");
+    }
+    catch ( ... ) {
+        testFail("OS time_t conversion exception for value 10 years hence");
+    }
+
     return testDone();
 }
diff --git a/src/libCom/test/fdmgrTest.c b/src/libCom/test/fdmgrTest.c
index 86857c6f5..e41784ccf 100644
--- a/src/libCom/test/fdmgrTest.c
+++ b/src/libCom/test/fdmgrTest.c
@@ -74,13 +74,13 @@ void testTimer (fdctx *pfdm, double delay)
 
     epicsTimeGetCurrent (&begin);
     cbs.done = 0;
-    tmo.tv_sec = (unsigned long) delay;
+    tmo.tv_sec = (time_t) delay;
     tmo.tv_usec = (unsigned long) ((delay - tmo.tv_sec) * uSecPerSec);
     aid = fdmgr_add_timeout (pfdm, &tmo, alarmCB, &cbs);
     verify (aid!=fdmgrNoAlarm);
 
     while (!cbs.done) {
-        tmo.tv_sec = (unsigned long) delay;
+        tmo.tv_sec = (time_t) delay;
         tmo.tv_usec = (unsigned long) ((delay - tmo.tv_sec) * uSecPerSec);
         status = fdmgr_pend_event (pfdm, &tmo);
         verify (status==0);
diff --git a/src/libCom/timer/timerPrivate.h b/src/libCom/timer/timerPrivate.h
index c60939851..55291309c 100644
--- a/src/libCom/timer/timerPrivate.h
+++ b/src/libCom/timer/timerPrivate.h
@@ -105,7 +105,7 @@ private:
     epicsTime exceptMsgTimeStamp;
     bool cancelPending;
     static const double exceptMsgMinPeriod;
-    void printExceptMsg ( const char * pName, 
+    void printExceptMsg ( const char * pName,
                 const type_info & type );
 	timerQueue ( const timerQueue & );
     timerQueue & operator = ( const timerQueue & );