diff --git a/std/concurrency.d b/std/concurrency.d
index e60aff1aac8..9d548ad020f 100644
--- a/std/concurrency.d
+++ b/std/concurrency.d
@@ -75,7 +75,6 @@ private
     import core.sync.mutex;
     import core.sync.condition;
     import std.algorithm;
-    import std.datetime;
     import std.exception;
     import std.range;
     import std.string;
@@ -1373,11 +1372,12 @@ private:
 
         override bool wait( Duration period ) nothrow
         {
+            import core.time;
             scope(exit) notified = false;
 
-            for( auto limit = Clock.currSystemTick + period;
+            for( auto limit = TickDuration.currSystemTick + period;
                  !notified && !period.isNegative;
-                 period = limit - Clock.currSystemTick )
+                 period = limit - TickDuration.currSystemTick )
             {
                 yield();
             }
@@ -2047,7 +2047,8 @@ private
 
             static if( timedWait )
             {
-                auto limit = Clock.currSystemTick + period;
+                import core.time;
+                auto limit = TickDuration.currSystemTick + period;
             }
 
             while( true )
@@ -2095,7 +2096,7 @@ private
                     {
                         static if( timedWait )
                         {
-                            period = limit - Clock.currSystemTick;
+                            period = limit - TickDuration.currSystemTick;
                         }
                         continue;
                     }
diff --git a/std/datetime.d b/std/datetime.d
index 9edac57a63c..8769b2ca0bd 100644
--- a/std/datetime.d
+++ b/std/datetime.d
@@ -27333,31 +27333,15 @@ private:
     }
 
 
-    static immutable LocalTime _localTime = new immutable(LocalTime)();
-    // Use low-lock singleton pattern with _tzsetWasCalled (see http://dconf.org/talks/simcha.html)
-    static bool _lowLock;
-    static shared bool _tzsetWasCalled;
-
-
     // This is done so that we can maintain purity in spite of doing an impure
     // operation the first time that LocalTime() is called.
     static immutable(LocalTime) singleton() @trusted
     {
-        if(!_lowLock)
-        {
-            synchronized
-            {
-                if(!_tzsetWasCalled)
-                {
-                    tzset();
-                    _tzsetWasCalled = true;
-                }
-            }
-
-            _lowLock = true;
-        }
-
-        return _localTime;
+        import std.concurrency : initOnce;
+        static instance = new immutable(LocalTime)();
+        static shared bool guard;
+        initOnce!guard({tzset(); return true;}());
+        return instance;
     }
 }
 
diff --git a/std/parallelism.d b/std/parallelism.d
index 161ba943213..8f461bece68 100644
--- a/std/parallelism.d
+++ b/std/parallelism.d
@@ -3273,24 +3273,13 @@ terminating the main thread.
 */
 @property TaskPool taskPool() @trusted
 {
-    static bool initialized;
-    __gshared static TaskPool pool;
-
-    if(!initialized)
-    {
-        synchronized(typeid(TaskPool))
-        {
-            if(!pool)
-            {
-                pool = new TaskPool(defaultPoolThreads);
-                pool.isDaemon = true;
-            }
-        }
-
-        initialized = true;
-    }
-
-    return pool;
+    import std.concurrency : initOnce;
+    __gshared TaskPool pool;
+    return initOnce!pool({
+        auto p = new TaskPool(defaultPoolThreads);
+        p.isDaemon = true;
+        return p;
+    }());
 }
 
 private shared uint _defaultPoolThreads;