diff --git a/dora-frontend/src/aliasck.rs b/dora-frontend/src/aliasck.rs
index 86af9a8da..5a05fd089 100644
--- a/dora-frontend/src/aliasck.rs
+++ b/dora-frontend/src/aliasck.rs
@@ -132,7 +132,7 @@ fn expand_type(
         | SourceType::This
         | SourceType::TypeParam(..) => ty,
 
-        SourceType::GenericAssoc(..) | SourceType::Any | SourceType::Ptr => {
+        SourceType::GenericAssoc { .. } | SourceType::Any | SourceType::Ptr => {
             panic!("unexpected type = {:?}", ty);
         }
     }
diff --git a/dora-frontend/src/extensiondefck.rs b/dora-frontend/src/extensiondefck.rs
index a48fe4541..316b609ae 100644
--- a/dora-frontend/src/extensiondefck.rs
+++ b/dora-frontend/src/extensiondefck.rs
@@ -78,7 +78,7 @@ pub fn package_for_type(sa: &Sema, ty: SourceType) -> Option<PackageDefinitionId
         SourceType::Enum(id, ..) => Some(sa.enum_(id).package_id),
         SourceType::TraitObject(id, ..) => Some(sa.trait_(id).package_id),
         SourceType::Alias(id, ..) => Some(sa.alias(id).package_id),
-        SourceType::Assoc(..) | SourceType::GenericAssoc(..) => unimplemented!(),
+        SourceType::Assoc(..) | SourceType::GenericAssoc { .. } => unimplemented!(),
     }
 }
 
@@ -106,7 +106,7 @@ impl<'x> ExtensionCheck<'x> {
             | SourceType::Ptr
             | SourceType::This
             | SourceType::Assoc(..)
-            | SourceType::GenericAssoc(..) => {
+            | SourceType::GenericAssoc { .. } => {
                 unreachable!()
             }
             SourceType::Error
@@ -243,7 +243,7 @@ fn discover_type_params(sa: &Sema, ty: SourceType, used_type_params: &mut FixedB
         SourceType::TypeParam(tp_id) => {
             used_type_params.insert(tp_id.index());
         }
-        SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc(..) => {
+        SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc { .. } => {
             unreachable!()
         }
     }
diff --git a/dora-frontend/src/impldefck.rs b/dora-frontend/src/impldefck.rs
index d0ace8bfa..b47ea6062 100644
--- a/dora-frontend/src/impldefck.rs
+++ b/dora-frontend/src/impldefck.rs
@@ -21,7 +21,7 @@ fn check_impl_definition(sa: &Sema, impl_: &ImplDefinition) {
         | SourceType::Ptr
         | SourceType::This
         | SourceType::Assoc(..)
-        | SourceType::GenericAssoc(..) => {
+        | SourceType::GenericAssoc { .. } => {
             unreachable!()
         }
         SourceType::Error
@@ -424,7 +424,7 @@ fn trait_and_impl_arg_ty_compatible(
         SourceType::Alias(..)
         | SourceType::Any
         | SourceType::Ptr
-        | SourceType::GenericAssoc(..) => unreachable!(),
+        | SourceType::GenericAssoc { .. } => unreachable!(),
     }
 }
 
diff --git a/dora-frontend/src/parsety.rs b/dora-frontend/src/parsety.rs
index 89cd15e14..94802d2b5 100644
--- a/dora-frontend/src/parsety.rs
+++ b/dora-frontend/src/parsety.rs
@@ -105,7 +105,8 @@ pub enum ParsedTypeKind {
     This,
 
     Regular {
-        symbol: SymbolKind,
+        symbol: Option<SymbolKind>,
+        kind: Option<PathKind>,
         type_arguments: Vec<ParsedTypeArgument>,
     },
 
@@ -184,7 +185,8 @@ fn parse_trait_type_inner(
 
     match &parsed_ast.kind {
         ParsedTypeKind::Regular {
-            symbol: SymbolKind::Trait(trait_id),
+            symbol: Some(SymbolKind::Trait(trait_id)),
+            kind: None,
             type_arguments,
         } => {
             let trait_ty =
@@ -237,15 +239,15 @@ fn parse_type_regular(
     allow_self: bool,
     node: &ast::TypeRegularType,
 ) -> ParsedTypeKind {
-    let segment_kind = parse_path(sa, table, file_id, element, allow_self, node);
+    let path_kind = parse_path(sa, table, file_id, element, allow_self, node);
 
-    if segment_kind.is_err() {
+    if path_kind.is_err() {
         return ParsedTypeKind::Error;
     }
 
-    let segment_kind = segment_kind.unwrap();
+    let path_kind = path_kind.unwrap();
 
-    match segment_kind {
+    match path_kind {
         PathKind::Symbol(sym) => match sym {
             SymbolKind::Trait(..)
             | SymbolKind::Class(..)
@@ -262,7 +264,8 @@ fn parse_type_regular(
                 }
 
                 ParsedTypeKind::Regular {
-                    symbol: sym,
+                    symbol: Some(sym),
+                    kind: None,
                     type_arguments: Vec::new(),
                 }
             }
@@ -274,6 +277,12 @@ fn parse_type_regular(
             }
         },
 
+        PathKind::GenericAssoc { .. } => ParsedTypeKind::Regular {
+            symbol: None,
+            kind: Some(path_kind),
+            type_arguments: Vec::new(),
+        },
+
         PathKind::Self_ => ParsedTypeKind::This,
     }
 }
@@ -306,7 +315,8 @@ fn parse_type_regular_with_arguments(
     }
 
     ParsedTypeKind::Regular {
-        symbol,
+        symbol: Some(symbol),
+        kind: None,
         type_arguments,
     }
 }
@@ -369,8 +379,9 @@ fn convert_type_regular(sa: &Sema, file_id: SourceFileId, parsed_ty: &ParsedType
     let (sym, type_params) = match parsed_ty.kind {
         ParsedTypeKind::Regular {
             ref symbol,
+            kind: None,
             type_arguments: ref type_params,
-        } => (symbol.clone(), type_params),
+        } => (symbol.clone().expect("symbol expected"), type_params),
         _ => unreachable!(),
     };
 
@@ -660,7 +671,7 @@ fn check_type_inner(
     parsed_ty: &ParsedTypeAst,
 ) -> SourceType {
     match ty.clone() {
-        SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc(..) => {
+        SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc { .. } => {
             unreachable!()
         }
         SourceType::This => SourceType::This,
@@ -676,7 +687,7 @@ fn check_type_inner(
         | SourceType::Int32
         | SourceType::Int64 => {
             let symbol = match &parsed_ty.kind {
-                ParsedTypeKind::Regular { symbol, .. } => symbol.clone(),
+                ParsedTypeKind::Regular { symbol, .. } => symbol.clone().expect("symbol expected"),
                 _ => unreachable!(),
             };
 
@@ -754,7 +765,7 @@ fn check_type_record(
             ref symbol,
             type_arguments: ref type_params,
             ..
-        } => (symbol.clone(), type_params),
+        } => (symbol.clone().expect("symbol expected"), type_params),
         _ => unreachable!(),
     };
 
@@ -1151,7 +1162,7 @@ fn expand_st(
         | SourceType::TypeParam(..) => ty,
         SourceType::This => replace_self.expect("self expected"),
 
-        SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc(..) => {
+        SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc { .. } => {
             panic!("unexpected type = {:?}", ty);
             // unreachable!()
         }
diff --git a/dora-frontend/src/path.rs b/dora-frontend/src/path.rs
index 08be99d62..c3aeefbe8 100644
--- a/dora-frontend/src/path.rs
+++ b/dora-frontend/src/path.rs
@@ -4,12 +4,19 @@ use dora_parser::{ast, Span};
 
 use crate::access::sym_accessible_from;
 use crate::sema::{
-    parent_element_or_self, AliasDefinitionId, Element, Sema, SourceFileId, TypeParamId,
+    parent_element_or_self, AliasDefinitionId, Element, Sema, SourceFileId, TraitDefinitionId,
+    TypeParamId,
 };
 use crate::{ErrorMessage, ModuleSymTable, Name, SymbolKind};
 
+#[derive(Clone, Debug)]
 pub enum PathKind {
     Self_,
+    GenericAssoc {
+        tp_id: TypeParamId,
+        trait_id: TraitDefinitionId,
+        assoc_id: AliasDefinitionId,
+    },
     Symbol(SymbolKind),
 }
 
@@ -96,6 +103,7 @@ fn parse_path_ident(
     }
 
     let mut previous_sym = sym.expect("missing symbol");
+    let mut result: Option<PathKind> = None;
 
     for (idx, segment) in segments.iter().enumerate().skip(1) {
         if previous_sym.is_module() {
@@ -129,10 +137,17 @@ fn parse_path_ident(
         } else if let SymbolKind::TypeParam(id) = previous_sym {
             let name = expect_ident(sa, file_id, segment)?;
 
-            let avaiable = lookup_alias_on_type_param(sa, element, id, name).unwrap_or(Vec::new());
-
-            if avaiable.len() == 1 {
-                previous_sym = SymbolKind::Alias(avaiable[0]);
+            let mut available =
+                lookup_alias_on_type_param(sa, element, id, name).unwrap_or(Vec::new());
+
+            if available.len() == 1 {
+                let (trait_id, assoc_id) = available.pop().expect("element expected");
+                previous_sym = SymbolKind::Alias(available[0].1);
+                result = Some(PathKind::GenericAssoc {
+                    tp_id: id,
+                    trait_id,
+                    assoc_id,
+                });
             } else {
                 unimplemented!()
             }
@@ -146,7 +161,11 @@ fn parse_path_ident(
         }
     }
 
-    Ok(PathKind::Symbol(previous_sym))
+    if let Some(path_kind) = result {
+        Ok(path_kind)
+    } else {
+        Ok(PathKind::Symbol(previous_sym))
+    }
 }
 
 fn available_aliases<'a>(
@@ -174,7 +193,7 @@ fn lookup_alias_on_type_param<'a>(
     element: &'a dyn Element,
     id: TypeParamId,
     name: Name,
-) -> Option<Vec<AliasDefinitionId>> {
+) -> Option<Vec<(TraitDefinitionId, AliasDefinitionId)>> {
     let type_param_definition = element.type_param_definition();
     let mut results = Vec::with_capacity(2);
 
@@ -183,7 +202,7 @@ fn lookup_alias_on_type_param<'a>(
         let trait_ = sa.trait_(trait_id);
 
         if let Some(id) = trait_.alias_names().get(&name) {
-            results.push(*id);
+            results.push((trait_id, *id));
         }
     }
 
diff --git a/dora-frontend/src/sema/impl_matching.rs b/dora-frontend/src/sema/impl_matching.rs
index 5c6c12e90..ff88dcf21 100644
--- a/dora-frontend/src/sema/impl_matching.rs
+++ b/dora-frontend/src/sema/impl_matching.rs
@@ -65,7 +65,7 @@ pub fn implements_trait(
 
         SourceType::TypeParam(tp_id) => check_type_param_defs.implements_trait(sa, tp_id, trait_ty),
 
-        SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc(..) => {
+        SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc { .. } => {
             unreachable!()
         }
 
diff --git a/dora-frontend/src/sema/matching.rs b/dora-frontend/src/sema/matching.rs
index 09d99a346..49f12f489 100644
--- a/dora-frontend/src/sema/matching.rs
+++ b/dora-frontend/src/sema/matching.rs
@@ -236,7 +236,7 @@ fn match_concrete_types(
             _ => false,
         },
 
-        SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc(..) => {
+        SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc { .. } => {
             unimplemented!()
         }
 
diff --git a/dora-frontend/src/specialize.rs b/dora-frontend/src/specialize.rs
index efc455603..ed7836afc 100644
--- a/dora-frontend/src/specialize.rs
+++ b/dora-frontend/src/specialize.rs
@@ -103,7 +103,7 @@ pub fn replace_type(
         | SourceType::Float64
         | SourceType::Error => ty,
 
-        SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc(..) => unreachable!(),
+        SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc { .. } => unreachable!(),
     }
 }
 
@@ -221,7 +221,7 @@ pub fn specialize_ty_for_trait_object(
         | SourceType::Float64
         | SourceType::Error => ty,
 
-        SourceType::This | SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc(..) => {
+        SourceType::This | SourceType::Any | SourceType::Ptr | SourceType::GenericAssoc { .. } => {
             unreachable!()
         }
     }
@@ -311,7 +311,7 @@ pub fn specialize_for_element(
         SourceType::Any
         | SourceType::Ptr
         | SourceType::Assoc(..)
-        | SourceType::GenericAssoc(..) => unreachable!(),
+        | SourceType::GenericAssoc { .. } => unreachable!(),
     }
 }
 
diff --git a/dora-frontend/src/ty.rs b/dora-frontend/src/ty.rs
index 26e4004ce..c77b0093b 100644
--- a/dora-frontend/src/ty.rs
+++ b/dora-frontend/src/ty.rs
@@ -154,7 +154,12 @@ pub enum SourceType {
     Assoc(AliasDefinitionId, SourceTypeArray),
 
     // Some associated type on type parameter (T::X).
-    GenericAssoc(TraitDefinitionId, AliasDefinitionId, SourceTypeArray),
+    GenericAssoc {
+        tp_id: TypeParamId,
+        trait_id: TraitDefinitionId,
+        assoc_id: AliasDefinitionId,
+        type_params: SourceTypeArray,
+    },
 
     // Some lambda.
     Lambda(SourceTypeArray, Box<SourceType>),
@@ -186,7 +191,7 @@ impl SourceType {
             SourceType::Class(..) => TyKind::Class,
             SourceType::Unit | SourceType::Tuple(..) => TyKind::Tuple,
             SourceType::Assoc(..) => TyKind::Assoc,
-            SourceType::GenericAssoc(..) => TyKind::GenericAssoc,
+            SourceType::GenericAssoc { .. } => TyKind::GenericAssoc,
         }
     }
 
@@ -541,7 +546,7 @@ impl SourceType {
                 *self == other
             }
 
-            SourceType::GenericAssoc(..) => unimplemented!(),
+            SourceType::GenericAssoc { .. } => unimplemented!(),
         }
     }
 
@@ -559,7 +564,7 @@ impl SourceType {
             | SourceType::TraitObject(..)
             | SourceType::Lambda(..)
             | SourceType::TypeParam(_) => true,
-            SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc(..) => {
+            SourceType::Alias(..) | SourceType::Assoc(..) | SourceType::GenericAssoc { .. } => {
                 unreachable!()
             }
             SourceType::Enum(_, params)
@@ -645,7 +650,7 @@ impl SourceType {
             SourceType::Alias(..)
             | SourceType::TypeParam(_)
             | SourceType::Assoc(..)
-            | SourceType::GenericAssoc(..) => false,
+            | SourceType::GenericAssoc { .. } => false,
         }
     }
 }
@@ -666,7 +671,7 @@ pub fn contains_self(sa: &Sema, ty: SourceType) -> bool {
         | SourceType::TypeParam(..)
         | SourceType::Assoc(..) => false,
 
-        SourceType::Alias(..) | SourceType::GenericAssoc(..) => {
+        SourceType::Alias(..) | SourceType::GenericAssoc { .. } => {
             unimplemented!()
         }
         SourceType::Class(_, params)
@@ -1053,7 +1058,7 @@ impl<'a> SourceTypePrinter<'a> {
                 }
             }
 
-            SourceType::GenericAssoc(..) => unimplemented!(),
+            SourceType::GenericAssoc { .. } => unimplemented!(),
         }
     }
 }
diff --git a/dora-frontend/src/typeck/expr.rs b/dora-frontend/src/typeck/expr.rs
index 7c609cdeb..30f2cfc4e 100644
--- a/dora-frontend/src/typeck/expr.rs
+++ b/dora-frontend/src/typeck/expr.rs
@@ -737,7 +737,7 @@ fn check_expr_assign_unnamed_field(
         | SourceType::Lambda(..)
         | SourceType::Alias(..)
         | SourceType::Assoc(..)
-        | SourceType::GenericAssoc(..) => {
+        | SourceType::GenericAssoc { .. } => {
             let name = index.to_string();
             let expr_name = ck.ty_name(&object_type);
             let msg = ErrorMessage::UnknownField(name, expr_name);
@@ -899,7 +899,7 @@ pub(super) fn check_expr_dot(
         | SourceType::Tuple(..)
         | SourceType::Alias(..)
         | SourceType::Assoc(..)
-        | SourceType::GenericAssoc(..) => {}
+        | SourceType::GenericAssoc { .. } => {}
         SourceType::Class(cls_id, class_type_params) => {
             if let Some((field_id, _)) =
                 find_field_in_class(ck.sa, object_type.clone(), interned_name)
@@ -989,7 +989,7 @@ fn check_expr_dot_unnamed_field(
         | SourceType::Lambda(..)
         | SourceType::Alias(..)
         | SourceType::Assoc(..)
-        | SourceType::GenericAssoc(..) => {
+        | SourceType::GenericAssoc { .. } => {
             let name = index.to_string();
             let expr_name = ck.ty_name(&object_type);
             let msg = ErrorMessage::UnknownField(name, expr_name);
diff --git a/dora-frontend/src/typeck/function.rs b/dora-frontend/src/typeck/function.rs
index 858998f98..db0689f48 100644
--- a/dora-frontend/src/typeck/function.rs
+++ b/dora-frontend/src/typeck/function.rs
@@ -607,7 +607,7 @@ pub(super) fn arg_allows(
             arg_allows(sa, alias.ty(), arg, self_ty.clone())
         }
 
-        SourceType::Assoc(..) | SourceType::GenericAssoc(..) => unimplemented!(),
+        SourceType::Assoc(..) | SourceType::GenericAssoc { .. } => unimplemented!(),
     }
 }