diff --git a/types/bl/BufferList.d.ts b/types/bl/BufferList.d.ts
new file mode 100644
index 00000000000000..7c6fc050596bee
--- /dev/null
+++ b/types/bl/BufferList.d.ts
@@ -0,0 +1,38 @@
+/// <reference types="node" />
+
+declare class BufferList {
+    constructor(initialData?: Buffer | Buffer[] | BufferList | BufferList[] | string);
+
+    length: number;
+    append(buffer: Buffer | Buffer[] | BufferList | BufferList[] | string): BufferList;
+    get(index: number): number;
+    slice(start?: number, end?: number): Buffer;
+    shallowSlice(start?: number, end?: number): BufferList;
+    copy(dest: Buffer, destStart?: number, srcStart?: number, srcEnd?: number): Buffer;
+    duplicate(): BufferList;
+    consume(bytes?: number): void;
+    toString(encoding?: string, start?: number, end?: number): string;
+    indexOf(value: string | number | Uint8Array | BufferList | Buffer, byteOffset?: number, encoding?: string): number;
+    readDoubleBE(offset?: number): number;
+    readDoubleLE(offset?: number): number;
+    readFloatBE(offset?: number): number;
+    readFloatLE(offset?: number): number;
+    readInt32BE(offset?: number): number;
+    readInt32LE(offset?: number): number;
+    readUInt32BE(offset?: number): number;
+    readUInt32LE(offset?: number): number;
+    readInt16BE(offset?: number): number;
+    readInt16LE(offset?: number): number;
+    readUInt16BE(offset?: number): number;
+    readUInt16LE(offset?: number): number;
+    readInt8(offset: number): number;
+    readUInt8(offset: number): number;
+    readIntBE(offset: number): number;
+    readIntLE(offset: number): number;
+    readUIntBE(offset: number): number;
+    readUIntLE(offset: number): number;
+
+    static isBufferList(other: any): boolean;
+}
+
+export = BufferList;
diff --git a/types/bl/bl-tests.ts b/types/bl/bl-tests.ts
index 648f7b711ab34b..800fe8666f206d 100644
--- a/types/bl/bl-tests.ts
+++ b/types/bl/bl-tests.ts
@@ -1,73 +1,110 @@
-import BufferList = require('bl');
+import BufferListStream = require("bl");
+import BufferList = require("bl/BufferList");
 
-var bl: BufferList;
+var bls: BufferListStream;
 var buffer: Buffer;
 var offset: number;
 var num: number;
 var str: string;
 
-bl = new BufferList();
-bl = new BufferList(bl);
-bl = new BufferList([bl]);
-bl = new BufferList(Buffer.from('asdf'));
-bl = new BufferList([Buffer.from('asdf')]);
-bl = new BufferList('hi');
+BufferListStream.isBufferList({});
+
+// has Duplex methods
+bls.pause();
+bls.resume();
+
+var bl = new BufferList();
+
+// is assignable
+bl = bls.duplicate();
+
+// is not assignable as it lacks the Duplex methods
+var bls2: BufferListStream;
+bls2 = bl; // $ExpectError
+
+// does not have Duplex methods
+bl.pause(); // $ExpectError
+bl.resume(); // $ExpectError
 
 bl.append(buffer);
-num = bl.length;
-
-num = bl.get(num);
-
-buffer = bl.slice(num, num);
-buffer = bl.slice(num);
-buffer = bl.slice();
-bl.shallowSlice(0, 1).shallowSlice();
-
-bl.copy(buffer, num, num, num);
-bl.copy(buffer, num, num);
-bl.copy(buffer, num);
-bl.copy(buffer);
-
-bl = bl.duplicate();
-
-bl.consume();
-bl.consume(num);
-
-str = bl.toString(str, num, num);
-str = bl.toString(str, num);
-str = bl.toString(str);
-str = bl.toString();
-bl.indexOf('foo', 0, 'hex') === 1;
-bl.indexOf(Buffer.from('foo')) === 1;
-bl.indexOf(4) === 1;
-bl.indexOf(bl) === 1;
-bl.indexOf(new Uint8Array([1, 3, 4])) === 2;
-
-num = bl.readDoubleBE(offset);
-num = bl.readDoubleBE(offset);
-num = bl.readDoubleLE(offset);
-num = bl.readDoubleLE(offset);
-num = bl.readFloatBE(offset);
-num = bl.readFloatBE(offset);
-num = bl.readFloatLE(offset);
-num = bl.readFloatLE(offset);
-num = bl.readInt32BE(offset);
-num = bl.readInt32BE(offset);
-num = bl.readInt32LE(offset);
-num = bl.readInt32LE(offset);
-num = bl.readUInt32BE(offset);
-num = bl.readUInt32BE(offset);
-num = bl.readUInt32LE(offset);
-num = bl.readUInt32LE(offset);
-num = bl.readInt16BE(offset);
-num = bl.readInt16BE(offset);
-num = bl.readInt16LE(offset);
-num = bl.readInt16LE(offset);
-num = bl.readUInt16BE(offset);
-num = bl.readUInt16BE(offset);
-num = bl.readUInt16LE(offset);
-num = bl.readUInt16LE(offset);
-num = bl.readInt8(offset);
-num = bl.readInt8(offset);
-num = bl.readUInt8(offset);
-num = bl.readUInt8(offset);
+bl.append(bl);
+bl.append(bls);
+
+bls = new BufferListStream();
+bls = new BufferListStream(bls);
+bls = new BufferListStream([bls]);
+bls = new BufferListStream(Buffer.from("asdf"));
+bls = new BufferListStream([Buffer.from("asdf")]);
+bls = new BufferListStream("hi");
+
+bls.append(buffer);
+bls.append(bl);
+bls.append(bls);
+num = bls.length;
+
+num = bls.get(num);
+
+buffer = bls.slice(num, num);
+buffer = bls.slice(num);
+buffer = bls.slice();
+bls.shallowSlice(0, 1).shallowSlice();
+
+bls.copy(buffer, num, num, num);
+bls.copy(buffer, num, num);
+bls.copy(buffer, num);
+bls.copy(buffer);
+
+bls = bls.duplicate();
+
+bls.consume();
+bls.consume(num);
+
+str = bls.toString(str, num, num);
+str = bls.toString(str, num);
+str = bls.toString(str);
+str = bls.toString();
+bls.indexOf("foo", 0, "hex") === 1;
+bls.indexOf(Buffer.from("foo")) === 1;
+bls.indexOf(4) === 1;
+bls.indexOf(bls) === 1;
+bls.indexOf(new Uint8Array([1, 3, 4])) === 2;
+bls.indexOf(bl) === 0;
+bl.indexOf(bls) === 0;
+
+num = bls.readDoubleBE(offset);
+num = bls.readDoubleBE(offset);
+num = bls.readDoubleLE(offset);
+num = bls.readDoubleLE(offset);
+num = bls.readFloatBE(offset);
+num = bls.readFloatBE(offset);
+num = bls.readFloatLE(offset);
+num = bls.readFloatLE(offset);
+num = bls.readInt32BE(offset);
+num = bls.readInt32BE(offset);
+num = bls.readInt32LE(offset);
+num = bls.readInt32LE(offset);
+num = bls.readUInt32BE(offset);
+num = bls.readUInt32BE(offset);
+num = bls.readUInt32LE(offset);
+num = bls.readUInt32LE(offset);
+num = bls.readInt16BE(offset);
+num = bls.readInt16BE(offset);
+num = bls.readInt16LE(offset);
+num = bls.readInt16LE(offset);
+num = bls.readUInt16BE(offset);
+num = bls.readUInt16BE(offset);
+num = bls.readUInt16LE(offset);
+num = bls.readUInt16LE(offset);
+num = bls.readInt8(offset);
+num = bls.readInt8(offset);
+num = bls.readUInt8(offset);
+num = bls.readUInt8(offset);
+num = bls.readIntBE(offset);
+num = bls.readIntLE(offset);
+num = bls.readUIntBE(offset);
+num = bls.readUIntLE(offset);
+
+BufferListStream.isBufferList(bls); // $ExpectTrue
+BufferListStream.isBufferList({}); // $ExpectFalse
+BufferList.isBufferList(bl); // $ExpectTrue
+BufferList.isBufferList({}); // $ExpectFalse
diff --git a/types/bl/index.d.ts b/types/bl/index.d.ts
index 6ae80ffff061bd..4e1bf116f6fd36 100644
--- a/types/bl/index.d.ts
+++ b/types/bl/index.d.ts
@@ -1,38 +1,23 @@
-// Type definitions for BufferList v4.1
+// Type definitions for BufferList v5.0
 // Project: https://github.com/rvagg/bl
 // Definitions by: Bart van der Schoor <https://github.com/Bartvds>
 //                 Francis Gulotta <https://github.com/reconbot>
 //                 Ben Allfree <https://github.com/benallfree>
+//                 Alex Potsides <https://github.com/achingbrain>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 /// <reference types="node" />
 
-declare class BufferList {
-    constructor(initialData?: Buffer | Buffer[] | BufferList | BufferList[] | string);
+import BufferList = require("./BufferList");
+import { Duplex } from "readable-stream";
+
+interface BufferListStream extends Duplex, BufferList {}
 
-    length: number;
-    append(buffer: Buffer | Buffer[] | BufferList | BufferList[] | string): BufferList;
-    get(index: number): number;
-    slice(start?: number, end?: number): Buffer;
-    shallowSlice(start?: number, end?: number): BufferList;
-    copy(dest: Buffer, destStart?: number, srcStart?: number, srcEnd?: number): Buffer;
-    duplicate(): BufferList;
-    consume(bytes?: number): void;
-    toString(encoding?: string, start?: number, end?: number): string;
-    indexOf(value: string | number | Uint8Array | BufferList | Buffer, byteOffset?: number, encoding?: string): number;
-    readDoubleBE(offset?: number): number;
-    readDoubleLE(offset?: number): number;
-    readFloatBE(offset?: number): number;
-    readFloatLE(offset?: number): number;
-    readInt32BE(offset?: number): number;
-    readInt32LE(offset?: number): number;
-    readUInt32BE(offset?: number): number;
-    readUInt32LE(offset?: number): number;
-    readInt16BE(offset?: number): number;
-    readInt16LE(offset?: number): number;
-    readUInt16BE(offset?: number): number;
-    readUInt16LE(offset?: number): number;
-    readInt8(offset: number): number;
-    readUInt8(offset: number): number;
+declare class BufferListStream {
+    constructor(initialData?: Buffer | Buffer[] | BufferList | BufferList[] | string);
+    static isBufferList: (other: any) => boolean;
+    duplicate: () => BufferListStream;
+    shallowSlice(start?: number, end?: number): BufferListStream;
 }
-export = BufferList;
+
+export = BufferListStream;