diff --git a/app/src/main/java/com/danielkim/soundrecorder/RecordingService.java b/app/src/main/java/com/danielkim/soundrecorder/RecordingService.java
index a8b36a18..372ae62d 100644
--- a/app/src/main/java/com/danielkim/soundrecorder/RecordingService.java
+++ b/app/src/main/java/com/danielkim/soundrecorder/RecordingService.java
@@ -112,7 +112,7 @@ public void setFileNameAndPath(){
             count++;
 
             mFileName = getString(R.string.default_file_name)
-                    + "_" + (mDatabase.getCount() + count) + ".mp4";
+                    + "_" + (mDatabase.getCount() + count) + ".m4a";
             mFilePath = Environment.getExternalStorageDirectory().getAbsolutePath();
             mFilePath += "/SoundRecorder/" + mFileName;
 
diff --git a/app/src/main/java/com/danielkim/soundrecorder/adapters/FileViewerAdapter.java b/app/src/main/java/com/danielkim/soundrecorder/adapters/FileViewerAdapter.java
index 1d1418cf..9ba24c54 100644
--- a/app/src/main/java/com/danielkim/soundrecorder/adapters/FileViewerAdapter.java
+++ b/app/src/main/java/com/danielkim/soundrecorder/adapters/FileViewerAdapter.java
@@ -253,7 +253,7 @@ public void renameFileDialog (final int position) {
                 new DialogInterface.OnClickListener() {
                     public void onClick(DialogInterface dialog, int id) {
                         try {
-                            String value = input.getText().toString().trim() + ".mp4";
+                            String value = input.getText().toString().trim() + ".m4a";
                             rename(position, value);
 
                         } catch (Exception e) {
diff --git a/app/src/main/res/layout/dialog_rename_file.xml b/app/src/main/res/layout/dialog_rename_file.xml
index d92ac782..05418030 100644
--- a/app/src/main/res/layout/dialog_rename_file.xml
+++ b/app/src/main/res/layout/dialog_rename_file.xml
@@ -12,7 +12,7 @@
         android:layout_height="wrap_content" />
 
     <TextView
-        android:text=".mp4"
+        android:text=".m4a"
         android:id="@+id/textView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content" />
diff --git a/app/src/main/res/layout/fragment_media_playback.xml b/app/src/main/res/layout/fragment_media_playback.xml
index f1a82d7e..9a4d72df 100644
--- a/app/src/main/res/layout/fragment_media_playback.xml
+++ b/app/src/main/res/layout/fragment_media_playback.xml
@@ -30,7 +30,7 @@
                 android:layout_marginLeft="10dp"
                 android:layout_marginTop="7dp"
                 android:layout_marginBottom="7dp"
-                android:text="file_name.mp4"
+                android:text="file_name.m4a"
                 android:textSize="18sp"
                 android:fontFamily="sans-serif-condensed"/>