diff --git a/src/main/wacc/types.scala b/src/main/wacc/types.scala
index 41d4124..549d8a1 100644
--- a/src/main/wacc/types.scala
+++ b/src/main/wacc/types.scala
@@ -9,9 +9,11 @@ object types {
       case KnownType.Bool              => "bool"
       case KnownType.Char              => "char"
       case KnownType.String            => "string"
+      case KnownType.Array(?)          => "array"
       case KnownType.Array(elem)       => s"$elem[]"
+      case KnownType.Pair(?, ?)        => "pair"
       case KnownType.Pair(left, right) => s"pair($left, $right)"
-      case ?                           => "?"
+      case ?                           => "<unknown-type>"
     }
   }