diff --git a/src/types/type_param.rs b/src/types/type_param.rs
index d3c37aae8..f292e63c5 100644
--- a/src/types/type_param.rs
+++ b/src/types/type_param.rs
@@ -119,8 +119,8 @@ pub enum TypeArgError {
     // TODO It may become possible to combine this with ConstTypeError.
     #[error("Type argument {0:?} does not fit declared parameter {1:?}")]
     TypeMismatch(TypeArg, TypeParam),
-    /// Wrong number of type arguments.
-    // For now this only happens at the top level (TypeArgs of Op vs TypeParams of OpDef).
+    /// Wrong number of type arguments (actual vs expected).
+    // For now this only happens at the top level (TypeArgs of op/type vs TypeParams of Op/TypeDef).
     // However in the future it may be applicable to e.g. contents of Tuples too.
     #[error("Wrong number of type arguments: {0} vs expected {1} declared type parameters")]
     WrongNumber(usize, usize),