diff --git a/doomsday/sdk/libcore/src/data/time.cpp b/doomsday/sdk/libcore/src/data/time.cpp
index a0425e1490..6977a53526 100644
--- a/doomsday/sdk/libcore/src/data/time.cpp
+++ b/doomsday/sdk/libcore/src/data/time.cpp
@@ -313,11 +313,17 @@ String Time::asText(Format format) const
         }
         else if(format == BuildNumberAndSecondsSinceStart)
         {
-            DENG2_ASSERT(d->flags & Instance::HighPerformance);
-
-            TimeDelta const elapsed = d->highPerfElapsed;
+            TimeDelta elapsed;
+            if(d->flags.testFlag(Instance::HighPerformance))
+            {
+                elapsed = d->highPerfElapsed;
+            }
+            else if(d->flags.testFlag(Instance::DateTime))
+            {
+                elapsed = highPerfTimer.startedAt().deltaTo(Time(d->dateTime));
+            }
             int hours = elapsed.asHours();
-            double sec = elapsed - hours * 3600.0;
+            TimeDelta sec = elapsed - hours * 3600.0;
             if(hours > 0)
             {
                 return QString("#%1 %2h%3")