diff --git a/audio/2.0/IDevicesFactory.hal b/audio/2.0/IDevicesFactory.hal
index a4e6956..f1dc7d3 100644
--- a/audio/2.0/IDevicesFactory.hal
+++ b/audio/2.0/IDevicesFactory.hal
@@ -22,7 +22,7 @@
 interface IDevicesFactory {
     typedef android.hardware.audio@2.0::Result Result;
 
-    enum Device {
+    enum Device : int32_t {
         PRIMARY,
         A2DP,
         USB,
diff --git a/audio/2.0/IPrimaryDevice.hal b/audio/2.0/IPrimaryDevice.hal
index 6beddfe..f1dd56e 100644
--- a/audio/2.0/IPrimaryDevice.hal
+++ b/audio/2.0/IPrimaryDevice.hal
@@ -76,7 +76,7 @@
      */
     setBtScoWidebandEnabled(bool enabled) generates (Result retval);
 
-    enum TtyMode {
+    enum TtyMode : int32_t {
         OFF,
         VCO,
         HCO,
diff --git a/audio/2.0/types.hal b/audio/2.0/types.hal
index 9a5e4f1..7002f38 100644
--- a/audio/2.0/types.hal
+++ b/audio/2.0/types.hal
@@ -18,7 +18,7 @@
 
 import android.hardware.audio.common@2.0;
 
-enum Result {
+enum Result : int32_t {
     OK,
     NOT_INITIALIZED,
     INVALID_ARGUMENTS,
@@ -27,7 +27,7 @@
 };
 
 @export(name="audio_drain_type_t", value_prefix="AUDIO_DRAIN_")
-enum AudioDrain {
+enum AudioDrain : int32_t {
     /* drain() returns when all data has been played. */
     ALL,
     /* drain() returns a short time before all data from the current track has