diff --git a/tests/foo/1.0/IFoo.hal b/tests/foo/1.0/IFoo.hal
index 5cbacd2..c1c2c6b 100644
--- a/tests/foo/1.0/IFoo.hal
+++ b/tests/foo/1.0/IFoo.hal
@@ -97,4 +97,6 @@
     transpose2(ThreeStrings[5] in) generates (FiveStrings[3] out);
 
     sendVec(vec<uint8_t> data) generates (vec<uint8_t> data);
+
+    sendVecVec() generates (vec<vec<uint8_t>> vecvec);
 };