diff --git a/grammar.js b/grammar.js
index 1907a3a3..d660238f 100644
--- a/grammar.js
+++ b/grammar.js
@@ -529,7 +529,12 @@ module.exports = grammar({
     trait_bounds: $ => seq(
       ':',
       sepBy1('+', choice(
-        $._type,
+        prec(1, seq(
+          optional("~const"),
+          optional("async"),
+          optional("!"),
+          $._type
+        )),
         $.lifetime,
         $.higher_ranked_trait_bound,
       )),
diff --git a/test/corpus/declarations.txt b/test/corpus/declarations.txt
index 77195e86..de9b13c0 100644
--- a/test/corpus/declarations.txt
+++ b/test/corpus/declarations.txt
@@ -1909,6 +1909,35 @@ impl<T: AstDeref<Target: HasNodeId>> HasNodeId for T {}
     (type_identifier)
     (declaration_list)))
 
+================================================================================
+Trait bounds with modifiers
+================================================================================
+
+impl <T: !Y> Foo for Bar {}
+impl <T: ~const async Y> Foo for Bar {}
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (impl_item
+    (type_parameters
+      (type_parameter
+        (type_identifier)
+        (trait_bounds
+          (type_identifier))))
+    (type_identifier)
+    (type_identifier)
+    (declaration_list))
+  (impl_item
+    (type_parameters
+      (type_parameter
+        (type_identifier)
+        (trait_bounds
+          (type_identifier))))
+    (type_identifier)
+    (type_identifier)
+    (declaration_list)))
+
 ================================================================================
 Macro invocations inside trait declarations
 ================================================================================