diff --git a/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java b/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
index 129037143b..cfd82968f3 100644
--- a/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
+++ b/library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java
@@ -906,7 +906,9 @@ import java.io.IOException;
         mediaSource.maybeThrowSourceInfoRefreshError();
       } else {
         Window window = timeline.getPeriodWindow(newLoadingPeriodIndex);
-        long startPositionUs = loadingPeriod == null ? playbackInfo.positionUs : C.UNSET_TIME_US;
+        long startPositionUs = loadingPeriod == null ? playbackInfo.positionUs
+            : newLoadingPeriodIndex == window.startPeriodIndex ? C.UNSET_TIME_US
+            : 0;
         if (startPositionUs == C.UNSET_TIME_US) {
           // This is the first period of a new window or we don't have a start position, so seek to
           // the default position for the window.
diff --git a/library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java b/library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java
index 4cff6360e5..edf64051e0 100644
--- a/library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java
@@ -184,10 +184,7 @@ public final class DashMediaSource implements MediaSource {
 
   @Override
   public void releasePeriod(MediaPeriod mediaPeriod) {
-    int id = ((DashMediaPeriod) mediaPeriod).id;
-    if (id >= firstPeriodId) {
-      periodsById.remove(id);
-    }
+    periodsById.remove(((DashMediaPeriod) mediaPeriod).id);
   }
 
   @Override
@@ -348,7 +345,12 @@ public final class DashMediaSource implements MediaSource {
   private void processManifest() {
     // Update any periods.
     for (int i = 0; i < periodsById.size(); i++) {
-      periodsById.valueAt(i).updateManifest(manifest, periodsById.keyAt(i) - firstPeriodId);
+      int id = periodsById.keyAt(i);
+      if (id >= firstPeriodId) {
+        periodsById.valueAt(i).updateManifest(manifest, id - firstPeriodId);
+      } else {
+        // This period has been removed from the manifest so it doesn't need to be updated.
+      }
     }
     // Remove any pending simulated updates.
     handler.removeCallbacks(simulateManifestRefreshRunnable);