diff --git a/tests/0-timer.d b/tests/0-timer.d
index 61d032e..907e04b 100644
--- a/tests/0-timer.d
+++ b/tests/0-timer.d
@@ -19,13 +19,18 @@ void main()
 
 	auto tm = eventDriver.timers.create();
 	eventDriver.timers.wait(tm, (tm) nothrow @safe {
-		scope (failure) assert(false);
+		Duration dur;
+
+		{
+			scope (failure) assert(false);
+			dur = Clock.currTime(UTC()) - s_startTime;
+		}
 
-		auto dur = Clock.currTime(UTC()) - s_startTime;
 		assert(dur > 200.msecs);
-		assert(dur < 220.msecs);
+		assert(dur < 260.msecs);
+
+		s_startTime += dur;
 
-		s_startTime = Clock.currTime(UTC());
 		eventDriver.timers.set(tm, 100.msecs, 100.msecs);
 
 		void secondTier(TimerID timer) nothrow @safe {
diff --git a/tests/issue-25-periodic-timers.d b/tests/issue-25-periodic-timers.d
index 378687c..4477428 100644
--- a/tests/issue-25-periodic-timers.d
+++ b/tests/issue-25-periodic-timers.d
@@ -22,12 +22,15 @@ void main()
 	// first timer: one-shot 200ms
 	auto tm = eventDriver.timers.create();
 	eventDriver.timers.wait(tm, (tm) nothrow @safe {
-		scope (failure) assert(false);
-		writefln("First timer");
+		Duration dur;
+		{
+			scope (failure) assert(false);
+			writefln("First timer");
+			dur = Clock.currTime(UTC()) - s_startTime;
+		}
 
-		auto dur = Clock.currTime(UTC()) - s_startTime;
-		assert(dur > 200.msecs);
-		assert(dur < 220.msecs);
+		assert(dur >= 200.msecs);
+		assert(dur < 250.msecs);
 
 		timer1fired = true;
 	});