diff --git a/tests/foo/1.0/IFoo.hal b/tests/foo/1.0/IFoo.hal
index 42e9c17..8491cb0 100644
--- a/tests/foo/1.0/IFoo.hal
+++ b/tests/foo/1.0/IFoo.hal
@@ -38,7 +38,7 @@
     doSomethingElse(int32_t[15] param) generates (int32_t[32] something);
     doStuffAndReturnAString() generates (string something);
     mapThisVector(vec<int32_t> param) generates (vec<int32_t> something);
-    callMe(IFooCallback cb);
+    oneway callMe(IFooCallback cb);
     useAnEnum(SomeEnum zzz) generates (SomeEnum sleepy);
 
     haveAGooberVec(vec<Goober> param);