diff --git a/README.md b/README.md
index 27ee5fc..183ea38 100644
--- a/README.md
+++ b/README.md
@@ -96,6 +96,8 @@ pylyzer converts Python ASTs to Erg ASTs and passes them to Erg's type checker.
   * [x] `Union`
   * [x] `Optional`
   * [x] `list`
+  * [x] `dict`
+  * [x] `tuple`
   * [x] `Literal`
   * [ ] `TypedDict`
   * [ ] others
diff --git a/crates/py2erg/convert.rs b/crates/py2erg/convert.rs
index 9dcfe5c..51c0c65 100644
--- a/crates/py2erg/convert.rs
+++ b/crates/py2erg/convert.rs
@@ -14,7 +14,7 @@ use erg_compiler::erg_parser::ast::{
     NormalTuple, ParamPattern, Params, PosArg, PreDeclTypeSpec, ReDef, Record, RecordAttrs, Set,
     Signature, SimpleTypeSpec, SubrSignature, Tuple, TypeAscription, TypeBoundSpecs, TypeSpec,
     TypeSpecWithOp, UnaryOp, VarName, VarPattern, VarRecordAttr, VarRecordAttrs, VarRecordPattern,
-    VarSignature, VisModifierSpec, ConstPosArg,
+    VarSignature, VisModifierSpec, ConstPosArg, ConstDict, ConstKeyValue, TupleTypeSpec,
 };
 use erg_compiler::erg_parser::desugar::Desugarer;
 use erg_compiler::erg_parser::token::{Token, TokenKind, AS, DOT, EQUAL};
@@ -565,6 +565,41 @@ impl ASTConverter {
                 let len = ConstPosArg::new(len);
                 TypeSpec::poly(Identifier::private("Array!".into()), ConstArgs::new(vec![elem_t, len], None, vec![], None))
             }
+            "dict" => {
+                let ExpressionType::Tuple { mut elements } = args.node else {
+                    return Self::gen_dummy_type_spec(args.location);
+                };
+                let (l_brace, r_brace) = Self::gen_enclosure_tokens(TokenKind::LBrace, elements.iter(), args.location);
+                let key_t = self.convert_expr(elements.remove(0));
+                let key_t = match Parser::validate_const_expr(key_t) {
+                    Ok(key_t) => key_t,
+                    Err(err) => {
+                        let err = CompileError::new(err.into(), self.cfg.input.clone(), self.cur_namespace());
+                        self.errs.push(err);
+                        ConstExpr::Accessor(ConstAccessor::Local(Identifier::private("Obj".into())))
+                    }
+                };
+                let val_t = self.convert_expr(elements.remove(0));
+                let val_t = match Parser::validate_const_expr(val_t) {
+                    Ok(val_t) => val_t,
+                    Err(err) => {
+                        let err = CompileError::new(err.into(), self.cfg.input.clone(), self.cur_namespace());
+                        self.errs.push(err);
+                        ConstExpr::Accessor(ConstAccessor::Local(Identifier::private("Obj".into())))
+                    }
+                };
+                let dict = ConstPosArg::new(ConstExpr::Dict(ConstDict::new(l_brace, r_brace, vec![ConstKeyValue::new(key_t, val_t)])));
+                TypeSpec::poly(Identifier::private("Dict!".into()), ConstArgs::new(vec![dict], None, vec![], None))
+            }
+            "tuple" => {
+                let ExpressionType::Tuple { elements } = args.node else {
+                    return Self::gen_dummy_type_spec(args.location);
+                };
+                let parens = Self::gen_enclosure_tokens(TokenKind::LParen, elements.iter(), args.location);
+                let tys = elements.into_iter().map(|elem| self.convert_type_spec(elem)).collect();
+                let tuple = TupleTypeSpec::new(Some(parens), tys);
+                TypeSpec::Tuple(tuple)
+            }
             _ => Self::gen_dummy_type_spec(args.location),
         }
     }
@@ -653,6 +688,7 @@ impl ASTConverter {
         match expr.node {
             ExpressionType::Number { value } => {
                 let (kind, cont) = match value {
+                    Number::Integer { value } if value >= 0.into() => (TokenKind::NatLit, value.to_string()),
                     Number::Integer { value } => (TokenKind::IntLit, value.to_string()),
                     Number::Float { value } => (TokenKind::RatioLit, value.to_string()),
                     Number::Complex { .. } => {
diff --git a/tests/collections.py b/tests/collections.py
index 2e7630c..da3d694 100644
--- a/tests/collections.py
+++ b/tests/collections.py
@@ -10,7 +10,13 @@ union_arr.append(None) # ERR
 
 dic = {"a": 1}
 dic["b"] = 2
-
 _ = dic["a"]
 _ = dic["b"]
-_ = dic["c"] # ERR
\ No newline at end of file
+_ = dic["c"] # ERR
+
+dic2: dict[str, int] = {"a": 1}
+_ = dic2["c"] # OK
+
+t: tuple[int, str] = (1, "a")
+_ = t[0] == 1 # OK
+_ = t[1] == 1 # ERR
diff --git a/tests/test.rs b/tests/test.rs
index 1a807da..a100d9f 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -95,6 +95,6 @@ fn exec_casting() {
 }
 
 #[test]
-fn exec_collection() {
-    expect("tests/collections.py", 0, 3);
+fn exec_collections() {
+    expect("tests/collections.py", 0, 4);
 }