@@ -60,7 +60,7 @@ module Python
          | UnaryOp(unaryop op, expr operand)
          | Lambda(arguments args, expr body)
          | IfExp(expr test, expr body, expr orelse)
-         | Dict(expr* keys, expr* values)
+         | Dict(expr?* keys, expr* values)
          | Set(expr* elts)
          | ListComp(expr elt, comprehension* generators)
          | SetComp(expr elt, comprehension* generators)
 
@@ -340,12 +340,12 @@ def _parse_optional_attributes(self):
 
     def _parse_optional_field_quantifier(self):
         is_seq, is_opt = False, False
+        if self.cur_token.kind == TokenKind.Question:
+            is_opt = True
+            self._advance()
         if self.cur_token.kind == TokenKind.Asterisk:
             is_seq = True
             self._advance()
-        elif self.cur_token.kind == TokenKind.Question:
-            is_opt = True
-            self._advance()
         return is_seq, is_opt
 
     def _advance(self):
 
@@ -240,11 +240,7 @@ def visitField(self, field, parent, vis, depth, constructor=None):
         # don't box if we're doing Vec<T>, but do box if we're doing Vec<Option<Box<T>>>
         if fieldtype and fieldtype.boxed and (not (parent.product or field.seq) or field.opt):
             typ = f"Box<{typ}>"
-        if field.opt or (
-            # Add `Option` to allow `Dict.keys` to contain `None` for dictionary unpacking
-            # in a dict literal.
-            constructor == "Dict" and field.name == "keys"
-        ):
+        if field.opt:
             typ = f"Option<{typ}>"
         if field.seq:
             typ = f"Vec<{typ}>"
 
@@ -195,7 +195,7 @@ pub enum ExprKind<U = ()> {
         orelse: Box<Expr<U>>,
     },
     Dict {
-        keys: Vec<Option<Expr<U>>>,
+        keys: Vec<Option<Box<Expr<U>>>>,
         values: Vec<Expr<U>>,
     },
     Set {