diff --git a/keystore-engine/android_engine.cpp b/keystore-engine/android_engine.cpp
index fba2583..856194d 100644
--- a/keystore-engine/android_engine.cpp
+++ b/keystore-engine/android_engine.cpp
@@ -80,8 +80,7 @@
  * the argument on failure. This means we need to tell our scoped pointers when
  * we've transferred ownership, without triggering a warning by not using the
  * result of release(). */
-#define OWNERSHIP_TRANSFERRED(obj) \
-    typeof ((obj).release()) _dummy __attribute__((unused)) = (obj).release()
+#define OWNERSHIP_TRANSFERRED(obj) auto _dummy __attribute__((unused)) = (obj).release()
 
 const char* rsa_get_key_id(const RSA* rsa);