diff --git a/baselines/audioworklet.generated.d.ts b/baselines/audioworklet.generated.d.ts
index 0536e0e2b..f2e5107d0 100644
--- a/baselines/audioworklet.generated.d.ts
+++ b/baselines/audioworklet.generated.d.ts
@@ -57,6 +57,16 @@ interface QueuingStrategyInit {
     highWaterMark: number;
 }
 
+interface ReadableStreamBYOBReadDoneResult<T> {
+    done: true;
+    value: T | undefined;
+}
+
+interface ReadableStreamDefaultReadDoneResult {
+    done: true;
+    value: undefined;
+}
+
 interface ReadableStreamGetReaderOptions {
     /**
      * Creates a ReadableStreamBYOBReader and locks the stream to the new reader.
@@ -66,11 +76,6 @@ interface ReadableStreamGetReaderOptions {
     mode?: ReadableStreamReaderMode;
 }
 
-interface ReadableStreamReadDoneResult<T> {
-    done: true;
-    value?: T;
-}
-
 interface ReadableStreamReadValueResult<T> {
     done: false;
     value: T;
@@ -775,7 +780,7 @@ declare var ReadableStream: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader) */
 interface ReadableStreamBYOBReader extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/read) */
-    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamReadResult<T>>;
+    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamBYOBReadResult<T>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/releaseLock) */
     releaseLock(): void;
 }
@@ -820,7 +825,7 @@ declare var ReadableStreamDefaultController: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader) */
 interface ReadableStreamDefaultReader<R = any> extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/read) */
-    read(): Promise<ReadableStreamReadResult<R>>;
+    read(): Promise<ReadableStreamDefaultReadResult<R>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/releaseLock) */
     releaseLock(): void;
 }
@@ -1408,8 +1413,10 @@ type BufferSource = ArrayBufferView | ArrayBuffer;
 type DOMHighResTimeStamp = number;
 type EventListenerOrEventListenerObject = EventListener | EventListenerObject;
 type MessageEventSource = MessagePort;
+type ReadableStreamBYOBReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamBYOBReadDoneResult<T>;
 type ReadableStreamController<T> = ReadableStreamDefaultController<T> | ReadableByteStreamController;
-type ReadableStreamReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamReadDoneResult<T>;
+type ReadableStreamDefaultReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamDefaultReadDoneResult;
+type ReadableStreamReadResult<T> = ReadableStreamDefaultReadResult<T> | ReadableStreamBYOBReadResult<T>;
 type ReadableStreamReader<T> = ReadableStreamDefaultReader<T> | ReadableStreamBYOBReader;
 type Transferable = MessagePort | ReadableStream | WritableStream | TransformStream | ArrayBuffer;
 type CompressionFormat = "deflate" | "deflate-raw" | "gzip";
diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index 471cf5b24..44be8b6a7 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -1610,6 +1610,16 @@ interface RTCTransportStats extends RTCStats {
     tlsVersion?: string;
 }
 
+interface ReadableStreamBYOBReadDoneResult<T> {
+    done: true;
+    value: T | undefined;
+}
+
+interface ReadableStreamDefaultReadDoneResult {
+    done: true;
+    value: undefined;
+}
+
 interface ReadableStreamGetReaderOptions {
     /**
      * Creates a ReadableStreamBYOBReader and locks the stream to the new reader.
@@ -1619,11 +1629,6 @@ interface ReadableStreamGetReaderOptions {
     mode?: ReadableStreamReaderMode;
 }
 
-interface ReadableStreamReadDoneResult<T> {
-    done: true;
-    value?: T;
-}
-
 interface ReadableStreamReadValueResult<T> {
     done: false;
     value: T;
@@ -18633,7 +18638,7 @@ declare var ReadableStream: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader) */
 interface ReadableStreamBYOBReader extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/read) */
-    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamReadResult<T>>;
+    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamBYOBReadResult<T>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/releaseLock) */
     releaseLock(): void;
 }
@@ -18678,7 +18683,7 @@ declare var ReadableStreamDefaultController: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader) */
 interface ReadableStreamDefaultReader<R = any> extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/read) */
-    read(): Promise<ReadableStreamReadResult<R>>;
+    read(): Promise<ReadableStreamDefaultReadResult<R>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/releaseLock) */
     releaseLock(): void;
 }
@@ -28203,8 +28208,10 @@ type OptionalPostfixToken<T extends string> = ` ${T}` | "";
 type OptionalPrefixToken<T extends string> = `${T} ` | "";
 type PerformanceEntryList = PerformanceEntry[];
 type RTCRtpTransform = RTCRtpScriptTransform;
+type ReadableStreamBYOBReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamBYOBReadDoneResult<T>;
 type ReadableStreamController<T> = ReadableStreamDefaultController<T> | ReadableByteStreamController;
-type ReadableStreamReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamReadDoneResult<T>;
+type ReadableStreamDefaultReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamDefaultReadDoneResult;
+type ReadableStreamReadResult<T> = ReadableStreamDefaultReadResult<T> | ReadableStreamBYOBReadResult<T>;
 type ReadableStreamReader<T> = ReadableStreamDefaultReader<T> | ReadableStreamBYOBReader;
 type RenderingContext = CanvasRenderingContext2D | ImageBitmapRenderingContext | WebGLRenderingContext | WebGL2RenderingContext;
 type ReportList = Report[];
diff --git a/baselines/serviceworker.generated.d.ts b/baselines/serviceworker.generated.d.ts
index a1ef2b447..e1ea7f3fd 100644
--- a/baselines/serviceworker.generated.d.ts
+++ b/baselines/serviceworker.generated.d.ts
@@ -479,6 +479,16 @@ interface QueuingStrategyInit {
     highWaterMark: number;
 }
 
+interface ReadableStreamBYOBReadDoneResult<T> {
+    done: true;
+    value: T | undefined;
+}
+
+interface ReadableStreamDefaultReadDoneResult {
+    done: true;
+    value: undefined;
+}
+
 interface ReadableStreamGetReaderOptions {
     /**
      * Creates a ReadableStreamBYOBReader and locks the stream to the new reader.
@@ -488,11 +498,6 @@ interface ReadableStreamGetReaderOptions {
     mode?: ReadableStreamReaderMode;
 }
 
-interface ReadableStreamReadDoneResult<T> {
-    done: true;
-    value?: T;
-}
-
 interface ReadableStreamReadValueResult<T> {
     done: false;
     value: T;
@@ -4524,7 +4529,7 @@ declare var ReadableStream: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader) */
 interface ReadableStreamBYOBReader extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/read) */
-    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamReadResult<T>>;
+    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamBYOBReadResult<T>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/releaseLock) */
     releaseLock(): void;
 }
@@ -4569,7 +4574,7 @@ declare var ReadableStreamDefaultController: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader) */
 interface ReadableStreamDefaultReader<R = any> extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/read) */
-    read(): Promise<ReadableStreamReadResult<R>>;
+    read(): Promise<ReadableStreamDefaultReadResult<R>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/releaseLock) */
     releaseLock(): void;
 }
@@ -8575,8 +8580,10 @@ type OffscreenRenderingContext = OffscreenCanvasRenderingContext2D | ImageBitmap
 type OnErrorEventHandler = OnErrorEventHandlerNonNull | null;
 type PerformanceEntryList = PerformanceEntry[];
 type PushMessageDataInit = BufferSource | string;
+type ReadableStreamBYOBReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamBYOBReadDoneResult<T>;
 type ReadableStreamController<T> = ReadableStreamDefaultController<T> | ReadableByteStreamController;
-type ReadableStreamReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamReadDoneResult<T>;
+type ReadableStreamDefaultReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamDefaultReadDoneResult;
+type ReadableStreamReadResult<T> = ReadableStreamDefaultReadResult<T> | ReadableStreamBYOBReadResult<T>;
 type ReadableStreamReader<T> = ReadableStreamDefaultReader<T> | ReadableStreamBYOBReader;
 type ReportList = Report[];
 type RequestInfo = Request | string;
diff --git a/baselines/sharedworker.generated.d.ts b/baselines/sharedworker.generated.d.ts
index 533adff76..396148d3e 100644
--- a/baselines/sharedworker.generated.d.ts
+++ b/baselines/sharedworker.generated.d.ts
@@ -445,6 +445,16 @@ interface QueuingStrategyInit {
     highWaterMark: number;
 }
 
+interface ReadableStreamBYOBReadDoneResult<T> {
+    done: true;
+    value: T | undefined;
+}
+
+interface ReadableStreamDefaultReadDoneResult {
+    done: true;
+    value: undefined;
+}
+
 interface ReadableStreamGetReaderOptions {
     /**
      * Creates a ReadableStreamBYOBReader and locks the stream to the new reader.
@@ -454,11 +464,6 @@ interface ReadableStreamGetReaderOptions {
     mode?: ReadableStreamReaderMode;
 }
 
-interface ReadableStreamReadDoneResult<T> {
-    done: true;
-    value?: T;
-}
-
 interface ReadableStreamReadValueResult<T> {
     done: false;
     value: T;
@@ -4358,7 +4363,7 @@ declare var ReadableStream: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader) */
 interface ReadableStreamBYOBReader extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/read) */
-    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamReadResult<T>>;
+    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamBYOBReadResult<T>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/releaseLock) */
     releaseLock(): void;
 }
@@ -4403,7 +4408,7 @@ declare var ReadableStreamDefaultController: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader) */
 interface ReadableStreamDefaultReader<R = any> extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/read) */
-    read(): Promise<ReadableStreamReadResult<R>>;
+    read(): Promise<ReadableStreamDefaultReadResult<R>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/releaseLock) */
     releaseLock(): void;
 }
@@ -8581,8 +8586,10 @@ type NamedCurve = string;
 type OffscreenRenderingContext = OffscreenCanvasRenderingContext2D | ImageBitmapRenderingContext | WebGLRenderingContext | WebGL2RenderingContext;
 type OnErrorEventHandler = OnErrorEventHandlerNonNull | null;
 type PerformanceEntryList = PerformanceEntry[];
+type ReadableStreamBYOBReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamBYOBReadDoneResult<T>;
 type ReadableStreamController<T> = ReadableStreamDefaultController<T> | ReadableByteStreamController;
-type ReadableStreamReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamReadDoneResult<T>;
+type ReadableStreamDefaultReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamDefaultReadDoneResult;
+type ReadableStreamReadResult<T> = ReadableStreamDefaultReadResult<T> | ReadableStreamBYOBReadResult<T>;
 type ReadableStreamReader<T> = ReadableStreamDefaultReader<T> | ReadableStreamBYOBReader;
 type ReportList = Report[];
 type RequestInfo = Request | string;
diff --git a/baselines/webworker.generated.d.ts b/baselines/webworker.generated.d.ts
index b488068f4..5734d8c50 100644
--- a/baselines/webworker.generated.d.ts
+++ b/baselines/webworker.generated.d.ts
@@ -523,6 +523,16 @@ interface RTCEncodedVideoFrameMetadata {
     width?: number;
 }
 
+interface ReadableStreamBYOBReadDoneResult<T> {
+    done: true;
+    value: T | undefined;
+}
+
+interface ReadableStreamDefaultReadDoneResult {
+    done: true;
+    value: undefined;
+}
+
 interface ReadableStreamGetReaderOptions {
     /**
      * Creates a ReadableStreamBYOBReader and locks the stream to the new reader.
@@ -532,11 +542,6 @@ interface ReadableStreamGetReaderOptions {
     mode?: ReadableStreamReaderMode;
 }
 
-interface ReadableStreamReadDoneResult<T> {
-    done: true;
-    value?: T;
-}
-
 interface ReadableStreamReadValueResult<T> {
     done: false;
     value: T;
@@ -4848,7 +4853,7 @@ declare var ReadableStream: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader) */
 interface ReadableStreamBYOBReader extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/read) */
-    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamReadResult<T>>;
+    read<T extends ArrayBufferView>(view: T): Promise<ReadableStreamBYOBReadResult<T>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader/releaseLock) */
     releaseLock(): void;
 }
@@ -4893,7 +4898,7 @@ declare var ReadableStreamDefaultController: {
 /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader) */
 interface ReadableStreamDefaultReader<R = any> extends ReadableStreamGenericReader {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/read) */
-    read(): Promise<ReadableStreamReadResult<R>>;
+    read(): Promise<ReadableStreamDefaultReadResult<R>>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader/releaseLock) */
     releaseLock(): void;
 }
@@ -9308,8 +9313,10 @@ type OffscreenRenderingContext = OffscreenCanvasRenderingContext2D | ImageBitmap
 type OnErrorEventHandler = OnErrorEventHandlerNonNull | null;
 type PerformanceEntryList = PerformanceEntry[];
 type PushMessageDataInit = BufferSource | string;
+type ReadableStreamBYOBReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamBYOBReadDoneResult<T>;
 type ReadableStreamController<T> = ReadableStreamDefaultController<T> | ReadableByteStreamController;
-type ReadableStreamReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamReadDoneResult<T>;
+type ReadableStreamDefaultReadResult<T> = ReadableStreamReadValueResult<T> | ReadableStreamDefaultReadDoneResult;
+type ReadableStreamReadResult<T> = ReadableStreamDefaultReadResult<T> | ReadableStreamBYOBReadResult<T>;
 type ReadableStreamReader<T> = ReadableStreamDefaultReader<T> | ReadableStreamBYOBReader;
 type ReportList = Report[];
 type RequestInfo = Request | string;
diff --git a/inputfiles/addedTypes.jsonc b/inputfiles/addedTypes.jsonc
index e0b8ae7c9..b8124b7fd 100644
--- a/inputfiles/addedTypes.jsonc
+++ b/inputfiles/addedTypes.jsonc
@@ -1287,8 +1287,25 @@
                     }
                 }
             },
-            "ReadableStreamReadDoneResult": {
-                "name": "ReadableStreamReadDoneResult",
+            "ReadableStreamDefaultReadDoneResult": {
+                "name": "ReadableStreamDefaultReadDoneResult",
+                "members": {
+                    "member": {
+                        "done": {
+                            "name": "done",
+                            "overrideType": "true",
+                            "required": true
+                        },
+                        "value": {
+                            "name": "value",
+                            "overrideType": "undefined",
+                            "required": true
+                        }
+                    }
+                }
+            },
+            "ReadableStreamBYOBReadDoneResult": {
+                "name": "ReadableStreamBYOBReadDoneResult",
                 "typeParameters": [
                     {
                         "name": "T"
@@ -1303,7 +1320,8 @@
                         },
                         "value": {
                             "name": "value",
-                            "overrideType": "T"
+                            "overrideType": "T | undefined",
+                            "required": true
                         }
                     }
                 }
@@ -1521,7 +1539,7 @@
                 ]
             },
             {
-                "name": "ReadableStreamReadResult",
+                "name": "ReadableStreamDefaultReadResult",
                 "typeParameters": [
                     {
                         "name": "T"
@@ -1532,10 +1550,44 @@
                         "type": "ReadableStreamReadValueResult"
                     },
                     {
-                        "type": "ReadableStreamReadDoneResult"
+                        "type": "ReadableStreamDefaultReadDoneResult"
+                    }
+                ],
+                "overrideType": "ReadableStreamReadValueResult<T> | ReadableStreamDefaultReadDoneResult"
+            },
+            {
+                "name": "ReadableStreamBYOBReadResult",
+                "typeParameters": [
+                    {
+                        "name": "T"
+                    }
+                ],
+                "type": [
+                    {
+                        "type": "ReadableStreamReadValueResult"
+                    },
+                    {
+                        "type": "ReadableStreamBYOBReadDoneResult"
+                    }
+                ],
+                "overrideType": "ReadableStreamReadValueResult<T> | ReadableStreamBYOBReadDoneResult<T>"
+            },
+            {
+                "name": "ReadableStreamReadResult",
+                "typeParameters": [
+                    {
+                        "name": "T"
+                    }
+                ],
+                "type": [
+                    {
+                        "type": "ReadableStreamDefaultReadResult"
+                    },
+                    {
+                        "type": "ReadableStreamBYOBReadResult"
                     }
                 ],
-                "overrideType": "ReadableStreamReadValueResult<T> | ReadableStreamReadDoneResult<T>"
+                "overrideType": "ReadableStreamDefaultReadResult<T> | ReadableStreamBYOBReadResult<T>"
             },
             {
                 "name": "EventListenerOrEventListenerObject",
diff --git a/inputfiles/overridingTypes.jsonc b/inputfiles/overridingTypes.jsonc
index 21924841b..e4eba9822 100644
--- a/inputfiles/overridingTypes.jsonc
+++ b/inputfiles/overridingTypes.jsonc
@@ -2652,7 +2652,7 @@
                                             "overrideType": "T"
                                         }
                                     ],
-                                    "overrideType": "Promise<ReadableStreamReadResult<T>>"
+                                    "overrideType": "Promise<ReadableStreamBYOBReadResult<T>>"
                                 }
                             }
                         }
@@ -2690,7 +2690,7 @@
                         "read": {
                             "signature": {
                                 "0": {
-                                    "overrideType": "Promise<ReadableStreamReadResult<R>>"
+                                    "overrideType": "Promise<ReadableStreamDefaultReadResult<R>>"
                                 }
                             }
                         }