diff --git a/src/protocol/tests/utils.rs b/src/protocol/tests/utils.rs
index 5b1c07dd45fe71c3196c467b4d7bacd49b7c2e97..d024b850a84b2ccec71ed575d289726037684ae6 100644
--- a/src/protocol/tests/utils.rs
+++ b/src/protocol/tests/utils.rs
@@ -781,6 +781,7 @@ fn serialize_concrete_type(buffer: &mut String, heap: &Heap, def: DefinitionId,
         Definition::Function(definition) => &definition.poly_vars,
         Definition::Component(definition) => &definition.poly_vars,
         Definition::Struct(definition) => &definition.poly_vars,
+        Definition::Enum(definition) => &definition.poly_vars,
         _ => unreachable!("Error in testing utility: unexpected type for concrete type serialization"),
     };