diff --git a/sim/core/apl.go b/sim/core/apl.go
index 7b0f568cab..88741763e5 100644
--- a/sim/core/apl.go
+++ b/sim/core/apl.go
@@ -215,7 +215,7 @@ func (apl *APLRotation) DoNextAction(sim *Simulation) {
 		apl.unit.DoNothing()
 	}
 
-	apl.unit.DoneAPLLoop(sim, gcdReady)
+	apl.unit.DoneAPLLoop(sim, !gcdReady)
 }
 
 func (apl *APLRotation) getNextAction(sim *Simulation) *APLAction {
diff --git a/sim/core/gcd.go b/sim/core/gcd.go
index 6741047306..b6a08c02fe 100644
--- a/sim/core/gcd.go
+++ b/sim/core/gcd.go
@@ -110,7 +110,9 @@ func (unit *Unit) WaitUntil(sim *Simulation, readyTime time.Duration) {
 	if readyTime < sim.CurrentTime {
 		panic(unit.Label + ": cannot wait negative time")
 	}
-	unit.waitStartTime = sim.CurrentTime
+	if !unit.IsWaiting() {
+		unit.waitStartTime = sim.CurrentTime
+	}
 	unit.SetGCDTimer(sim, readyTime)
 	if sim.Log != nil && readyTime > sim.CurrentTime {
 		unit.Log(sim, "Pausing GCD for %s due to rotation / CDs.", readyTime-sim.CurrentTime)