diff --git a/source/ddbus/conv.d b/source/ddbus/conv.d
index c4891d5..1a85bdd 100644
--- a/source/ddbus/conv.d
+++ b/source/ddbus/conv.d
@@ -173,7 +173,7 @@ T readIter(T)(DBusMessageIter *iter) if (isInstanceOf!(BitFlags, T)) {
   alias TemplateArgsOf!T[0] E;
   alias OriginalType!E B;
 
-  B mask = only(EnumMembers!E).fold!((a, b) => a | b);
+  B mask = only(EnumMembers!E).fold!((a, b) => cast(B) (a | b));
 
   B value = readIter!B(iter);
   enforce(