diff --git a/src/include/taler_amount_lib.h b/src/include/taler_amount_lib.h
index 04aa00045..c9a35a2aa 100644
--- a/src/include/taler_amount_lib.h
+++ b/src/include/taler_amount_lib.h
@@ -402,7 +402,7 @@ TALER_amount_multiply (struct TALER_Amount *result,
  *         #GNUNET_NO if value was already normalized
  *         #GNUNET_SYSERR if value was invalid or could not be normalized
  */
-int
+enum GNUNET_GenericReturnValue
 TALER_amount_normalize (struct TALER_Amount *amount);