diff --git a/service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java b/service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java
index 57466a6..ceae9ba 100644
--- a/service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java
+++ b/service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java
@@ -31,7 +31,7 @@
 import com.android.net.module.util.BpfMap;
 import com.android.net.module.util.IBpfMap;
 import com.android.net.module.util.InterfaceParams;
-import com.android.net.module.util.Struct.U32;
+import com.android.net.module.util.Struct.S32;
 
 /**
  * Monitor interface added (without removed) and right interface name and its index to bpf map.
@@ -41,7 +41,7 @@
     // This is current path but may be changed soon.
     private static final String IFACE_INDEX_NAME_MAP_PATH =
             "/sys/fs/bpf/netd_shared/map_netd_iface_index_name_map";
-    private final IBpfMap<U32, InterfaceMapValue> mBpfMap;
+    private final IBpfMap<S32, InterfaceMapValue> mBpfMap;
     private final INetd mNetd;
     private final Handler mHandler;
     private final Dependencies mDeps;
@@ -64,10 +64,10 @@
     @VisibleForTesting
     public static class Dependencies {
         /** Create BpfMap for updating interface and index mapping. */
-        public IBpfMap<U32, InterfaceMapValue> getInterfaceMap() {
+        public IBpfMap<S32, InterfaceMapValue> getInterfaceMap() {
             try {
                 return new BpfMap<>(IFACE_INDEX_NAME_MAP_PATH, BpfMap.BPF_F_RDWR,
-                    U32.class, InterfaceMapValue.class);
+                    S32.class, InterfaceMapValue.class);
             } catch (ErrnoException e) {
                 Log.e(TAG, "Cannot create interface map: " + e);
                 return null;
@@ -126,7 +126,7 @@
         }
 
         try {
-            mBpfMap.updateEntry(new U32(iface.index), new InterfaceMapValue(ifaceName));
+            mBpfMap.updateEntry(new S32(iface.index), new InterfaceMapValue(ifaceName));
         } catch (ErrnoException e) {
             Log.e(TAG, "Unable to update entry for " + ifaceName + ", " + e);
         }
@@ -140,9 +140,9 @@
     }
 
     /** get interface name by interface index from bpf map */
-    public String getIfNameByIndex(final long index) {
+    public String getIfNameByIndex(final int index) {
         try {
-            final InterfaceMapValue value = mBpfMap.getValue(new U32(index));
+            final InterfaceMapValue value = mBpfMap.getValue(new S32(index));
             if (value == null) {
                 Log.e(TAG, "No if name entry for index " + index);
                 return null;
diff --git a/service-t/src/com/android/server/net/NetworkStatsService.java b/service-t/src/com/android/server/net/NetworkStatsService.java
index 807f5d7..39a705f 100644
--- a/service-t/src/com/android/server/net/NetworkStatsService.java
+++ b/service-t/src/com/android/server/net/NetworkStatsService.java
@@ -2896,9 +2896,8 @@
         BpfDump.dumpMap(statsMap, pw, mapName,
                 "ifaceIndex ifaceName tag_hex uid_int cnt_set rxBytes rxPackets txBytes txPackets",
                 (key, value) -> {
-                    final long ifIndex = key.ifaceIndex;
-                    final String ifName = mInterfaceMapUpdater.getIfNameByIndex(ifIndex);
-                    return ifIndex + " "
+                    final String ifName = mInterfaceMapUpdater.getIfNameByIndex(key.ifaceIndex);
+                    return key.ifaceIndex + " "
                             + (ifName != null ? ifName : "unknown") + " "
                             + "0x" + Long.toHexString(key.tag) + " "
                             + key.uid + " "
diff --git a/service-t/src/com/android/server/net/StatsMapKey.java b/service-t/src/com/android/server/net/StatsMapKey.java
index ea8d836..a26fa5b 100644
--- a/service-t/src/com/android/server/net/StatsMapKey.java
+++ b/service-t/src/com/android/server/net/StatsMapKey.java
@@ -33,11 +33,11 @@
     @Field(order = 2, type = Type.U32)
     public final long counterSet;
 
-    @Field(order = 3, type = Type.U32)
-    public final long ifaceIndex;
+    @Field(order = 3, type = Type.S32)
+    public final int ifaceIndex;
 
     public StatsMapKey(final long uid, final long tag, final long counterSet,
-            final long ifaceIndex) {
+            final int ifaceIndex) {
         this.uid = uid;
         this.tag = tag;
         this.counterSet = counterSet;
diff --git a/tests/unit/java/com/android/server/net/BpfInterfaceMapUpdaterTest.java b/tests/unit/java/com/android/server/net/BpfInterfaceMapUpdaterTest.java
index 83e6b5f..c730856 100644
--- a/tests/unit/java/com/android/server/net/BpfInterfaceMapUpdaterTest.java
+++ b/tests/unit/java/com/android/server/net/BpfInterfaceMapUpdaterTest.java
@@ -42,7 +42,7 @@
 import com.android.net.module.util.BaseNetdUnsolicitedEventListener;
 import com.android.net.module.util.IBpfMap;
 import com.android.net.module.util.InterfaceParams;
-import com.android.net.module.util.Struct.U32;
+import com.android.net.module.util.Struct.S32;
 import com.android.testutils.DevSdkIgnoreRule;
 import com.android.testutils.DevSdkIgnoreRunner;
 import com.android.testutils.TestBpfMap;
@@ -69,14 +69,14 @@
     private final TestLooper mLooper = new TestLooper();
     private BaseNetdUnsolicitedEventListener mListener;
     private BpfInterfaceMapUpdater mUpdater;
-    private IBpfMap<U32, InterfaceMapValue> mBpfMap =
-            spy(new TestBpfMap<>(U32.class, InterfaceMapValue.class));
+    private IBpfMap<S32, InterfaceMapValue> mBpfMap =
+            spy(new TestBpfMap<>(S32.class, InterfaceMapValue.class));
     @Mock private INetd mNetd;
     @Mock private Context mContext;
 
     private class TestDependencies extends BpfInterfaceMapUpdater.Dependencies {
         @Override
-        public IBpfMap<U32, InterfaceMapValue> getInterfaceMap() {
+        public IBpfMap<S32, InterfaceMapValue> getInterfaceMap() {
             return mBpfMap;
         }
 
@@ -114,7 +114,7 @@
                 ArgumentCaptor.forClass(BaseNetdUnsolicitedEventListener.class);
         verify(mNetd).registerUnsolicitedEventListener(listenerCaptor.capture());
         mListener = listenerCaptor.getValue();
-        verify(mBpfMap).updateEntry(eq(new U32(TEST_INDEX)),
+        verify(mBpfMap).updateEntry(eq(new S32(TEST_INDEX)),
                 eq(new InterfaceMapValue(TEST_INTERFACE_NAME)));
     }
 
@@ -124,7 +124,7 @@
 
         mListener.onInterfaceAdded(TEST_INTERFACE_NAME2);
         mLooper.dispatchAll();
-        verify(mBpfMap).updateEntry(eq(new U32(TEST_INDEX2)),
+        verify(mBpfMap).updateEntry(eq(new S32(TEST_INDEX2)),
                 eq(new InterfaceMapValue(TEST_INTERFACE_NAME2)));
 
         // Check that when onInterfaceRemoved is called, nothing happens.
@@ -135,7 +135,7 @@
 
     @Test
     public void testGetIfNameByIndex() throws Exception {
-        mBpfMap.updateEntry(new U32(TEST_INDEX), new InterfaceMapValue(TEST_INTERFACE_NAME));
+        mBpfMap.updateEntry(new S32(TEST_INDEX), new InterfaceMapValue(TEST_INTERFACE_NAME));
         assertEquals(TEST_INTERFACE_NAME, mUpdater.getIfNameByIndex(TEST_INDEX));
     }
 
@@ -146,7 +146,7 @@
 
     @Test
     public void testGetIfNameByIndexException() throws Exception {
-        doThrow(new ErrnoException("", EPERM)).when(mBpfMap).getValue(new U32(TEST_INDEX));
+        doThrow(new ErrnoException("", EPERM)).when(mBpfMap).getValue(new S32(TEST_INDEX));
         assertNull(mUpdater.getIfNameByIndex(TEST_INDEX));
     }
 
@@ -163,8 +163,8 @@
 
     @Test
     public void testDump() throws ErrnoException {
-        mBpfMap.updateEntry(new U32(TEST_INDEX), new InterfaceMapValue(TEST_INTERFACE_NAME));
-        mBpfMap.updateEntry(new U32(TEST_INDEX2), new InterfaceMapValue(TEST_INTERFACE_NAME2));
+        mBpfMap.updateEntry(new S32(TEST_INDEX), new InterfaceMapValue(TEST_INTERFACE_NAME));
+        mBpfMap.updateEntry(new S32(TEST_INDEX2), new InterfaceMapValue(TEST_INTERFACE_NAME2));
 
         final String dump = getDump();
         assertDumpContains(dump, "IfaceIndexNameMap: OK");