diff --git a/Cargo.lock b/Cargo.lock
index aac473191f..eafec00d34 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1839,9 +1839,9 @@ checksum = "56dee185309b50d1f11bfedef0fe6d036842e3fb77413abef29f8f8d1c5d4c1c"
 
 [[package]]
 name = "ungrammar"
-version = "1.9.2"
+version = "1.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "58a02e2041a872d56354e843e8e86e6b946fc8e7dc32982fcdc335e29eb4cc8b"
+checksum = "f5901372c0f3a6a1a9d880aef134c8eaf5e54409343637508c0a344270b42d7b"
 
 [[package]]
 name = "unicase"
diff --git a/crates/parser/src/grammar/items/traits.rs b/crates/parser/src/grammar/items/traits.rs
index d076974ed2..d3327271cc 100644
--- a/crates/parser/src/grammar/items/traits.rs
+++ b/crates/parser/src/grammar/items/traits.rs
@@ -40,6 +40,10 @@ pub(super) fn impl_(p: &mut Parser) {
         type_params::opt_generic_param_list(p);
     }
 
+    // test impl_def_const
+    // impl const Send for X {}
+    p.eat(T![const]);
+
     // FIXME: never type
     // impl ! {}
 
diff --git a/crates/syntax/test_data/parser/inline/ok/0161_impl_def_const.rast b/crates/syntax/test_data/parser/inline/ok/0161_impl_def_const.rast
new file mode 100644
index 0000000000..dcd39535b4
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0161_impl_def_const.rast
@@ -0,0 +1,24 @@
+SOURCE_FILE@0..25
+  IMPL@0..24
+    IMPL_KW@0..4 "impl"
+    WHITESPACE@4..5 " "
+    CONST_KW@5..10 "const"
+    WHITESPACE@10..11 " "
+    PATH_TYPE@11..15
+      PATH@11..15
+        PATH_SEGMENT@11..15
+          NAME_REF@11..15
+            IDENT@11..15 "Send"
+    WHITESPACE@15..16 " "
+    FOR_KW@16..19 "for"
+    WHITESPACE@19..20 " "
+    PATH_TYPE@20..21
+      PATH@20..21
+        PATH_SEGMENT@20..21
+          NAME_REF@20..21
+            IDENT@20..21 "X"
+    WHITESPACE@21..22 " "
+    ASSOC_ITEM_LIST@22..24
+      L_CURLY@22..23 "{"
+      R_CURLY@23..24 "}"
+  WHITESPACE@24..25 "\n"
diff --git a/crates/syntax/test_data/parser/inline/ok/0161_impl_def_const.rs b/crates/syntax/test_data/parser/inline/ok/0161_impl_def_const.rs
new file mode 100644
index 0000000000..8d68864693
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0161_impl_def_const.rs
@@ -0,0 +1 @@
+impl const Send for X {}