diff --git a/services/mediametrics/AudioPowerUsage.cpp b/services/mediametrics/AudioPowerUsage.cpp
index b1615bd..b1648d9 100644
--- a/services/mediametrics/AudioPowerUsage.cpp
+++ b/services/mediametrics/AudioPowerUsage.cpp
@@ -160,7 +160,7 @@
         return true; //ignore unknown device
     }
 
-    for (auto item : mItems) {
+    for (const auto& item : mItems) {
         int32_t item_type = 0, item_device = 0;
         double item_volume = 0.;
         int64_t item_duration_ns = 0;
@@ -259,8 +259,8 @@
         const int64_t endCallNs = item->getTimestamp();
         const int64_t durationNs = endCallNs - mDeviceTimeNs;
         if (durationNs > 0) {
-            mDeviceVolume = (mDeviceVolume * (mVolumeTimeNs - mDeviceTimeNs) +
-                    mVoiceVolume * (endCallNs - mVolumeTimeNs)) / durationNs;
+            mDeviceVolume = (mDeviceVolume * double(mVolumeTimeNs - mDeviceTimeNs) +
+                    mVoiceVolume * double(endCallNs - mVolumeTimeNs)) / durationNs;
             saveAsItem_l(mPrimaryDevice, durationNs, VOICE_CALL_TYPE, mDeviceVolume);
         }
     } else if (mode == "AUDIO_MODE_IN_CALL") { // entering call mode
@@ -287,8 +287,8 @@
         const int64_t timeNs = item->getTimestamp();
         const int64_t durationNs = timeNs - mDeviceTimeNs;
         if (durationNs > 0) {
-            mDeviceVolume = (mDeviceVolume * (mVolumeTimeNs - mDeviceTimeNs) +
-                    mVoiceVolume * (timeNs - mVolumeTimeNs)) / durationNs;
+            mDeviceVolume = (mDeviceVolume * double(mVolumeTimeNs - mDeviceTimeNs) +
+                    mVoiceVolume * double(timeNs - mVolumeTimeNs)) / durationNs;
             mVolumeTimeNs = timeNs;
         }
     }
@@ -318,8 +318,8 @@
         const int64_t endDeviceNs = item->getTimestamp();
         const int64_t durationNs = endDeviceNs - mDeviceTimeNs;
         if (durationNs > 0) {
-            mDeviceVolume = (mDeviceVolume * (mVolumeTimeNs - mDeviceTimeNs) +
-                    mVoiceVolume * (endDeviceNs - mVolumeTimeNs)) / durationNs;
+            mDeviceVolume = (mDeviceVolume * double(mVolumeTimeNs - mDeviceTimeNs) +
+                    mVoiceVolume * double(endDeviceNs - mVolumeTimeNs)) / durationNs;
             saveAsItem_l(mPrimaryDevice, durationNs, VOICE_CALL_TYPE, mDeviceVolume);
         }
         // reset statistics
@@ -391,4 +391,4 @@
     return { ss.str(), slot };
 }
 
-} // namespace android
+} // namespace android::mediametrics