diff --git a/crates/ra_assists/src/ast_transform.rs b/crates/ra_assists/src/ast_transform.rs
index 4001ca73c3e8..18f3ec683b61 100644
--- a/crates/ra_assists/src/ast_transform.rs
+++ b/crates/ra_assists/src/ast_transform.rs
@@ -64,12 +64,11 @@ impl<'a> SubstituteTypeParams<'a> {
                     let default = k.default(source_scope.db)?;
                     Some((
                         k,
-                        ast::make::type_arg(
+                        ast::make::type_ref(
                             &default
                                 .display_source_code(source_scope.db, source_scope.module()?.into())
                                 .ok()?,
                         )
-                        .type_ref()?,
                     ))
                 }
             })
diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index 8981cbe33983..d0e960fb497c 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -13,8 +13,8 @@ pub fn name_ref(text: &str) -> ast::NameRef {
     ast_from_text(&format!("fn f() {{ {}; }}", text))
 }
 
-pub fn type_arg(text: &str) -> ast::TypeArg {
-    ast_from_text(&format!("impl F<{}> for G {{}}", text))
+pub fn type_ref(text: &str) -> ast::TypeRef {
+    ast_from_text(&format!("impl {} for D {{}};", text))
 }
 
 pub fn path_segment(name_ref: ast::NameRef) -> ast::PathSegment {