diff --git a/trunk_parser/src/ast.rs b/trunk_parser/src/ast.rs
index d884c4d..75d8283 100644
--- a/trunk_parser/src/ast.rs
+++ b/trunk_parser/src/ast.rs
@@ -10,6 +10,9 @@ pub enum Type {
     Union(Vec<ByteString>),
     Intersection(Vec<ByteString>),
     Void,
+    Null,
+    True,
+    False,
 }
 
 #[derive(Debug, Eq, PartialEq, Clone)]
diff --git a/trunk_parser/src/parser/ident.rs b/trunk_parser/src/parser/ident.rs
index 0bf4d64..230422c 100644
--- a/trunk_parser/src/parser/ident.rs
+++ b/trunk_parser/src/parser/ident.rs
@@ -57,9 +57,10 @@ impl Parser {
 
     pub(crate) fn type_with_static(&mut self) -> ParseResult<ByteString> {
         Ok(match self.current.kind {
-            TokenKind::Static => {
+            TokenKind::Static | TokenKind::Null | TokenKind::True | TokenKind::False => {
+                let str = self.current.kind.to_string();
                 self.next();
-                "static".into()
+                str.into()
             }
             _ => self.full_name_maybe_type_keyword()?,
         })
diff --git a/trunk_parser/src/parser/mod.rs b/trunk_parser/src/parser/mod.rs
index 3b7e0a1..97315bc 100644
--- a/trunk_parser/src/parser/mod.rs
+++ b/trunk_parser/src/parser/mod.rs
@@ -163,6 +163,9 @@ impl Parser {
 
         Ok(match &id[..] {
             b"void" => Type::Void,
+            b"null" => Type::Null,
+            b"true" => Type::True,
+            b"false" => Type::False,
             _ => Type::Plain(id),
         })
     }
@@ -4104,6 +4107,48 @@ mod tests {
         assert_ast("<?php a:", &[Statement::Label { label: "a".into() }]);
     }
 
+    #[test]
+    fn null_return_type() {
+        assert_ast(
+            "<?php function a(): null {}",
+            &[Statement::Function {
+                name: "a".into(),
+                params: vec![],
+                body: vec![],
+                return_type: Some(Type::Null),
+                by_ref: false,
+            }],
+        );
+    }
+
+    #[test]
+    fn true_return_type() {
+        assert_ast(
+            "<?php function a(): true {}",
+            &[Statement::Function {
+                name: "a".into(),
+                params: vec![],
+                body: vec![],
+                return_type: Some(Type::True),
+                by_ref: false,
+            }],
+        );
+    }
+
+    #[test]
+    fn false_return_type() {
+        assert_ast(
+            "<?php function a(): false {}",
+            &[Statement::Function {
+                name: "a".into(),
+                params: vec![],
+                body: vec![],
+                return_type: Some(Type::False),
+                by_ref: false,
+            }],
+        );
+    }
+
     fn assert_ast(source: &str, expected: &[Statement]) {
         let mut lexer = Lexer::new(None);
         let tokens = lexer.tokenize(source).unwrap();