diff --git a/types/serialport/index.d.ts b/types/serialport/index.d.ts
index c1a81376fa..73296d82e2 100644
--- a/types/serialport/index.d.ts
+++ b/types/serialport/index.d.ts
@@ -2,6 +2,7 @@
 // Project: https://github.com/EmergingTechnologyAdvisors/node-serialport
 // Definitions by: Jeremy Foster <https://github.com/codefoster>
 //                 Andrew Pearson <https://github.com/apearson>
+//                 Cameron Tacklind <https://github.com/cinderblock>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 /// <reference types="node" />
@@ -100,7 +101,7 @@ declare namespace SerialPort {
 			constructor(options: {delimiter: string | Buffer | number[], includeDelimiter?: boolean});
 		}
 		class Readline extends Delimiter {
-			constructor(options: {delimiter: string | Buffer | number[], encoding?: 'ascii'|'utf8'|'utf16le'|'ucs2'|'base64'|'binary'|'hex'});
+			constructor(options: {delimiter: string | Buffer | number[], encoding?: 'ascii'|'utf8'|'utf16le'|'ucs2'|'base64'|'binary'|'hex', includeDelimiter?: boolean});
 		}
 		class Ready extends Stream.Transform {
 			constructor(options: {delimiter: string | Buffer | number[]});
diff --git a/types/serialport/serialport-tests.ts b/types/serialport/serialport-tests.ts
index d6541a63c2..476199b506 100644
--- a/types/serialport/serialport-tests.ts
+++ b/types/serialport/serialport-tests.ts
@@ -105,8 +105,8 @@ function test_parsers() {
 
     const ByteLengthParser = new SerialPort.parsers.ByteLength({length: 8});
     const CCTalkParser = new SerialPort.parsers.CCTalk();
-    const DelimiterParser = new SerialPort.parsers.Delimiter({ delimiter: Buffer.from('EOL') });
-    const ReadlineParser = new SerialPort.parsers.Readline({ delimiter: '\r\n' });
+    const DelimiterParser = new SerialPort.parsers.Delimiter({ delimiter: Buffer.from('EOL'), includeDelimiter: true });
+    const ReadlineParser = new SerialPort.parsers.Readline({ delimiter: '\r\n', includeDelimiter: false });
     const ReadyParser = new SerialPort.parsers.Ready({ delimiter: 'READY' });
     const RegexParser = new SerialPort.parsers.Regex({regex: /.*/});
 
diff --git a/types/serialport/v6/index.d.ts b/types/serialport/v6/index.d.ts
index 2f5f8fc55d..2ada54c85f 100644
--- a/types/serialport/v6/index.d.ts
+++ b/types/serialport/v6/index.d.ts
@@ -90,7 +90,7 @@ declare namespace SerialPort {
 			constructor(options: {delimiter: string | Buffer | number[], includeDelimiter?: boolean});
 		}
 		class Readline extends Delimiter {
-			constructor(options: {delimiter: string | Buffer | number[], encoding?: 'ascii'|'utf8'|'utf16le'|'ucs2'|'base64'|'binary'|'hex'});
+			constructor(options: {delimiter: string | Buffer | number[], encoding?: 'ascii'|'utf8'|'utf16le'|'ucs2'|'base64'|'binary'|'hex', includeDelimiter?: boolean});
 		}
 		class Ready extends Stream.Transform {
 			constructor(options: {data: string | Buffer | number[]});