diff --git a/src/grammar.ron b/src/grammar.ron
index 9912f969889..78277183000 100644
--- a/src/grammar.ron
+++ b/src/grammar.ron
@@ -132,6 +132,7 @@ Grammar(
         "FIELD_EXPR",
         "REF_EXPR",
         "DEREF_EXPR",
+        "NOT_EXPR",
         "LAMBDA_EXPR",
         "STRUCT_LIT",
         "STRUCT_LIT_FIELD",
diff --git a/src/grammar/expressions.rs b/src/grammar/expressions.rs
index ed9236b02db..c638e8b993f 100644
--- a/src/grammar/expressions.rs
+++ b/src/grammar/expressions.rs
@@ -103,11 +103,13 @@ fn let_stmt(p: &mut Parser) {
 }
 
 fn prefix_expr(p: &mut Parser) -> Option<CompletedMarker> {
-    match p.current() {
-        AMPERSAND => Some(ref_expr(p)),
-        STAR => Some(deref_expr(p)),
-        _ => atom_expr(p),
-    }
+    let done = match p.current() {
+        AMPERSAND => ref_expr(p),
+        STAR => deref_expr(p),
+        EXCL => not_expr(p),
+        _ => return atom_expr(p),
+    };
+    Some(done)
 }
 
 // test ref_expr
@@ -136,6 +138,18 @@ fn deref_expr(p: &mut Parser) -> CompletedMarker {
     m.complete(p, DEREF_EXPR)
 }
 
+// test not_expr
+// fn foo() {
+//     !!true;
+// }
+fn not_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(EXCL));
+    let m = p.start();
+    p.bump();
+    expr(p);
+    m.complete(p, NOT_EXPR)
+}
+
 fn atom_expr(p: &mut Parser) -> Option<CompletedMarker> {
     match literal(p) {
         Some(m) => return Some(m),
diff --git a/src/syntax_kinds/generated.rs b/src/syntax_kinds/generated.rs
index 35d9640fab6..746316ed567 100644
--- a/src/syntax_kinds/generated.rs
+++ b/src/syntax_kinds/generated.rs
@@ -123,6 +123,7 @@ pub enum SyntaxKind {
     FIELD_EXPR,
     REF_EXPR,
     DEREF_EXPR,
+    NOT_EXPR,
     LAMBDA_EXPR,
     STRUCT_LIT,
     STRUCT_LIT_FIELD,
@@ -287,6 +288,7 @@ impl SyntaxKind {
             FIELD_EXPR => &SyntaxInfo { name: "FIELD_EXPR" },
             REF_EXPR => &SyntaxInfo { name: "REF_EXPR" },
             DEREF_EXPR => &SyntaxInfo { name: "DEREF_EXPR" },
+            NOT_EXPR => &SyntaxInfo { name: "NOT_EXPR" },
             LAMBDA_EXPR => &SyntaxInfo { name: "LAMBDA_EXPR" },
             STRUCT_LIT => &SyntaxInfo { name: "STRUCT_LIT" },
             STRUCT_LIT_FIELD => &SyntaxInfo { name: "STRUCT_LIT_FIELD" },
diff --git a/tests/data/parser/inline/0066_not_expr.rs b/tests/data/parser/inline/0066_not_expr.rs
new file mode 100644
index 00000000000..4c97fd9a641
--- /dev/null
+++ b/tests/data/parser/inline/0066_not_expr.rs
@@ -0,0 +1,3 @@
+fn foo() {
+    !!true;
+}
diff --git a/tests/data/parser/inline/0066_not_expr.txt b/tests/data/parser/inline/0066_not_expr.txt
new file mode 100644
index 00000000000..3e950969ec4
--- /dev/null
+++ b/tests/data/parser/inline/0066_not_expr.txt
@@ -0,0 +1,24 @@
+FILE@[0; 25)
+  FN_ITEM@[0; 25)
+    FN_KW@[0; 2)
+    NAME@[2; 6)
+      WHITESPACE@[2; 3)
+      IDENT@[3; 6) "foo"
+    PARAM_LIST@[6; 9)
+      L_PAREN@[6; 7)
+      R_PAREN@[7; 8)
+      WHITESPACE@[8; 9)
+    BLOCK@[9; 25)
+      L_CURLY@[9; 10)
+      EXPR_STMT@[10; 23)
+        NOT_EXPR@[10; 21)
+          WHITESPACE@[10; 15)
+          EXCL@[15; 16)
+          NOT_EXPR@[16; 21)
+            EXCL@[16; 17)
+            LITERAL@[17; 21)
+              TRUE_KW@[17; 21)
+        SEMI@[21; 22)
+        WHITESPACE@[22; 23)
+      R_CURLY@[23; 24)
+      WHITESPACE@[24; 25)