diff --git a/audio/effect/2.0/IDownmixEffect.hal b/audio/effect/2.0/IDownmixEffect.hal
index 817e14c..06409a3 100644
--- a/audio/effect/2.0/IDownmixEffect.hal
+++ b/audio/effect/2.0/IDownmixEffect.hal
@@ -20,7 +20,7 @@
 import IEffect;
 
 interface IDownmixEffect extends IEffect {
-    enum Type {
+    enum Type : int32_t {
         STRIP, // throw away the extra channels
         FOLD   // mix the extra channels with FL/FR
     };
diff --git a/audio/effect/2.0/INoiseSuppressionEffect.hal b/audio/effect/2.0/INoiseSuppressionEffect.hal
index 58e439f..ae2bfb5 100644
--- a/audio/effect/2.0/INoiseSuppressionEffect.hal
+++ b/audio/effect/2.0/INoiseSuppressionEffect.hal
@@ -20,7 +20,7 @@
 import IEffect;
 
 interface INoiseSuppressionEffect extends IEffect {
-    enum Level {
+    enum Level : int32_t {
         LOW,
         MEDIUM,
         HIGH
@@ -36,7 +36,7 @@
      */
     getSuppressionLevel() generates (Result retval, Level level);
 
-    enum Type {
+    enum Type : int32_t {
         SINGLE_CHANNEL,
         MULTI_CHANNEL
     };
diff --git a/audio/effect/2.0/IPresetReverbEffect.hal b/audio/effect/2.0/IPresetReverbEffect.hal
index 58dfd40..2237bc4 100644
--- a/audio/effect/2.0/IPresetReverbEffect.hal
+++ b/audio/effect/2.0/IPresetReverbEffect.hal
@@ -20,7 +20,7 @@
 import IEffect;
 
 interface IPresetReverbEffect extends IEffect {
-    enum Preset {
+    enum Preset : int32_t {
         NONE,        // no reverb or reflections
         SMALLROOM,   // a small room less than five meters in length
         MEDIUMROOM,  // a medium room with a length of ten meters or less
diff --git a/audio/effect/2.0/IVisualizerEffect.hal b/audio/effect/2.0/IVisualizerEffect.hal
index 70dabf9..79dc9ee 100644
--- a/audio/effect/2.0/IVisualizerEffect.hal
+++ b/audio/effect/2.0/IVisualizerEffect.hal
@@ -20,7 +20,7 @@
 import IEffect;
 
 interface IVisualizerEffect extends IEffect {
-    enum CaptureSizeRange {
+    enum CaptureSizeRange : int32_t {
         MAX = 1024,  // maximum capture size in samples
         MIN = 128    // minimum capture size in samples
     };
@@ -35,7 +35,7 @@
      */
     getCaptureSize() generates (Result retval, uint16_t captureSize);
 
-    enum ScalingMode {
+    enum ScalingMode : int32_t {
         // Keep in sync with SCALING_MODE_... in
         // frameworks/base/media/java/android/media/audiofx/Visualizer.java
         NORMALIZED = 0,
@@ -62,7 +62,7 @@
      */
     getLatency() generates (Result retval, uint32_t latencyMs);
 
-    enum MeasurementMode {
+    enum MeasurementMode : int32_t {
         // Keep in sync with MEASUREMENT_MODE_... in
         // frameworks/base/media/java/android/media/audiofx/Visualizer.java
         NONE = 0x0,
diff --git a/audio/effect/2.0/types.hal b/audio/effect/2.0/types.hal
index 35015b2..ad7f4ce 100644
--- a/audio/effect/2.0/types.hal
+++ b/audio/effect/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,
@@ -110,7 +110,7 @@
  * +----------------+--------+--------------------------------------------------
  */
 @export(name="", value_prefix="EFFECT_FLAG_")
-enum EffectFlags {
+enum EffectFlags : int32_t {
     // Insert mode
     TYPE_SHIFT = 0,
     TYPE_SIZE = 3,
@@ -229,7 +229,7 @@
 };
 
 @export(name="effect_buffer_access_e", value_prefix="EFFECT_BUFFER_")
-enum EffectBufferAccess {
+enum EffectBufferAccess : int32_t {
     ACCESS_WRITE,
     ACCESS_READ,
     ACCESS_ACCUMULATE
@@ -239,7 +239,7 @@
  * Determines what fields of EffectBufferConfig need to be considered.
  */
 @export(name="", value_prefix="EFFECT_CONFIG_")
-enum EffectConfigParameters {
+enum EffectConfigParameters : int32_t {
     BUFFER = 0x0001,    // buffer field
     SMP_RATE = 0x0002,  // samplingRate
     CHANNELS = 0x0004,  // channels
@@ -267,7 +267,7 @@
 };
 
 @export(name="effect_feature_e", value_prefix="EFFECT_FEATURE_")
-enum EffectFeature {
+enum EffectFeature : int32_t {
     AUX_CHANNELS, // supports auxiliary channels
                   // (e.g. dual mic noise suppressor)
     CNT