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
     };