diff --git a/src/debug.pr b/src/debug.pr
index 0250f1f4..a778ecee 100644
--- a/src/debug.pr
+++ b/src/debug.pr
@@ -874,7 +874,7 @@ export def type_to_str(tpe: &typechecking::Type, full_name: bool = false) -> Str
         case typechecking::TypeKind::TUNION, typechecking::TypeKind::VARIANT
             return variant_t_to_string(tpe, full_name)
         case typechecking::TypeKind::INTERFACE_IMPL
-            return type_to_str(tpe.tpe, full_name) + "@" + type_to_str(tpe.intf, full_name) + "#" + tpe.module.module
+            return type_to_str(tpe.tpe, full_name) + "/" + type_to_str(tpe.intf, full_name) + "#" + tpe.module.module
         case
             error(tpe.kind, "\n")
             assert