diff --git a/core/java/android/net/NetworkStats.java b/core/java/android/net/NetworkStats.java
index 5b883a0741..e5f32735b0 100644
--- a/core/java/android/net/NetworkStats.java
+++ b/core/java/android/net/NetworkStats.java
@@ -19,6 +19,7 @@ package android.net;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.SystemClock;
+import android.util.Log;
 import android.util.SparseBooleanArray;
 
 import com.android.internal.util.Objects;
@@ -38,6 +39,8 @@ import java.util.HashSet;
  * @hide
  */
 public class NetworkStats implements Parcelable {
+    private static final String TAG = "NetworkStats";
+
     /** {@link #iface} value when interface details unavailable. */
     public static final String IFACE_ALL = null;
     /** {@link #uid} value when UID details unavailable. */
@@ -397,7 +400,10 @@ public class NetworkStats implements Parcelable {
                 if (enforceMonotonic
                         && (entry.rxBytes < 0 || entry.rxPackets < 0 || entry.txBytes < 0
                                 || entry.txPackets < 0 || entry.operations < 0)) {
-                    throw new IllegalArgumentException("found non-monotonic values");
+                    Log.v(TAG, "lhs=" + this);
+                    Log.v(TAG, "rhs=" + value);
+                    throw new IllegalArgumentException(
+                            "found non-monotonic values at lhs[" + i + "] - rhs[" + j + "]");
                 }
                 if (clampNegative) {
                     entry.rxBytes = Math.max(0, entry.rxBytes);
diff --git a/core/java/android/net/NetworkStatsHistory.java b/core/java/android/net/NetworkStatsHistory.java
index b19949e39d..d07d8990d7 100644
--- a/core/java/android/net/NetworkStatsHistory.java
+++ b/core/java/android/net/NetworkStatsHistory.java
@@ -482,12 +482,12 @@ public class NetworkStatsHistory implements Parcelable {
         for (int i = start; i < bucketCount; i++) {
             pw.print(prefix);
             pw.print("  bucketStart="); pw.print(bucketStart[i]);
-            if (activeTime != null) pw.print(" activeTime="); pw.print(activeTime[i]);
-            if (rxBytes != null) pw.print(" rxBytes="); pw.print(rxBytes[i]);
-            if (rxPackets != null) pw.print(" rxPackets="); pw.print(rxPackets[i]);
-            if (txBytes != null) pw.print(" txBytes="); pw.print(txBytes[i]);
-            if (txPackets != null) pw.print(" txPackets="); pw.print(txPackets[i]);
-            if (operations != null) pw.print(" operations="); pw.print(operations[i]);
+            if (activeTime != null) { pw.print(" activeTime="); pw.print(activeTime[i]); }
+            if (rxBytes != null) { pw.print(" rxBytes="); pw.print(rxBytes[i]); }
+            if (rxPackets != null) { pw.print(" rxPackets="); pw.print(rxPackets[i]); }
+            if (txBytes != null) { pw.print(" txBytes="); pw.print(txBytes[i]); }
+            if (txPackets != null) { pw.print(" txPackets="); pw.print(txPackets[i]); }
+            if (operations != null) { pw.print(" operations="); pw.print(operations[i]); }
             pw.println();
         }
     }
diff --git a/services/java/com/android/server/net/NetworkStatsService.java b/services/java/com/android/server/net/NetworkStatsService.java
index 80ae9bc6cb..bb0a0d132b 100644
--- a/services/java/com/android/server/net/NetworkStatsService.java
+++ b/services/java/com/android/server/net/NetworkStatsService.java
@@ -707,7 +707,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
                     mLastPersistUidSnapshot, uidSnapshot, true);
             if (forcePersist || persistUidDelta.getTotalBytes() > persistThreshold) {
                 writeUidStatsLocked();
-                mLastPersistNetworkSnapshot = networkSnapshot;
+                mLastPersistUidSnapshot = networkSnapshot;
             }
         }