diff --git a/dev/demux.html b/dev/demux.html
index bfbdb68..daa726c 100644
--- a/dev/demux.html
+++ b/dev/demux.html
@@ -14,12 +14,21 @@
 			source: new Mediabunny.BlobSource(file),
 		});
 
+		const audioTrack = await input.getPrimaryAudioTrack();
+		
+		const sink = new Mediabunny.EncodedPacketSink(audioTrack);
+		for await (const packet of sink.packets()) {
+			console.log(packet)
+		}
+
+		/*
 		const videoTrack = await input.getPrimaryVideoTrack();
 		const sink = new Mediabunny.VideoSampleSink(videoTrack);
 
 		const sample = await sink.getSample(0);
 
 		console.log(sample);
+		*/
 
 		/*
 		const sink = new Mediabunny.EncodedPacketSink(videoTrack);
diff --git a/src/misc.ts b/src/misc.ts
index 3df6e2f..c39de08 100644
--- a/src/misc.ts
+++ b/src/misc.ts
@@ -155,7 +155,7 @@ export const writeBits = (bytes: Uint8Array, start: number, end: number, value:
 };
 
 export const toUint8Array = (source: AllowSharedBufferSource): Uint8Array => {
-	if (source instanceof Uint8Array) {
+	if (source.constructor === Uint8Array) { // We want a true Uint8Array, not something that extends it like Buffer
 		return source;
 	} else if (source instanceof ArrayBuffer) {
 		return new Uint8Array(source);
@@ -165,7 +165,7 @@ export const toUint8Array = (source: AllowSharedBufferSource): Uint8Array => {
 };
 
 export const toDataView = (source: AllowSharedBufferSource) => {
-	if (source instanceof DataView) {
+	if (source.constructor === DataView) {
 		return source;
 	} else if (source instanceof ArrayBuffer) {
 		return new DataView(source);
diff --git a/src/reader.ts b/src/reader.ts
index 5624343..6c30f3c 100644
--- a/src/reader.ts
+++ b/src/reader.ts
@@ -149,16 +149,32 @@ export class FileSlice {
 	}
 }
 
+const checkIsInRange = (slice: FileSlice, bytesToRead: number) => {
+	if (slice.filePos < slice.start || slice.filePos + bytesToRead > slice.end) {
+		throw new RangeError(
+			`Tried reading [${slice.filePos}, ${slice.filePos + bytesToRead}), but slice is`
+			+ ` [${slice.start}, ${slice.end}).`,
+		);
+	}
+};
+
 export const readBytes = (slice: FileSlice, length: number) => {
+	checkIsInRange(slice, length);
+
 	const bytes = slice.bytes.subarray(slice.bufferPos, slice.bufferPos + length);
 	slice.bufferPos += length;
 
 	return bytes;
 };
 
-export const readU8 = (slice: FileSlice) => slice.view.getUint8(slice.bufferPos++);
+export const readU8 = (slice: FileSlice) => {
+	checkIsInRange(slice, 1);
+	return slice.view.getUint8(slice.bufferPos++);
+};
 
 export const readU16 = (slice: FileSlice, littleEndian: boolean) => {
+	checkIsInRange(slice, 2);
+
 	const value = slice.view.getUint16(slice.bufferPos, littleEndian);
 	slice.bufferPos += 2;
 
@@ -166,6 +182,8 @@ export const readU16 = (slice: FileSlice, littleEndian: boolean) => {
 };
 
 export const readU16Be = (slice: FileSlice) => {
+	checkIsInRange(slice, 2);
+
 	const value = slice.view.getUint16(slice.bufferPos, false);
 	slice.bufferPos += 2;
 
@@ -173,6 +191,8 @@ export const readU16Be = (slice: FileSlice) => {
 };
 
 export const readU24Be = (slice: FileSlice) => {
+	checkIsInRange(slice, 3);
+
 	const value = getUint24(slice.view, slice.bufferPos, false);
 	slice.bufferPos += 3;
 
@@ -180,6 +200,8 @@ export const readU24Be = (slice: FileSlice) => {
 };
 
 export const readI16Be = (slice: FileSlice) => {
+	checkIsInRange(slice, 2);
+
 	const value = slice.view.getInt16(slice.bufferPos, false);
 	slice.bufferPos += 2;
 
@@ -187,6 +209,8 @@ export const readI16Be = (slice: FileSlice) => {
 };
 
 export const readU32 = (slice: FileSlice, littleEndian: boolean) => {
+	checkIsInRange(slice, 4);
+
 	const value = slice.view.getUint32(slice.bufferPos, littleEndian);
 	slice.bufferPos += 4;
 
@@ -194,6 +218,8 @@ export const readU32 = (slice: FileSlice, littleEndian: boolean) => {
 };
 
 export const readU32Be = (slice: FileSlice) => {
+	checkIsInRange(slice, 4);
+
 	const value = slice.view.getUint32(slice.bufferPos, false);
 	slice.bufferPos += 4;
 
@@ -201,6 +227,8 @@ export const readU32Be = (slice: FileSlice) => {
 };
 
 export const readU32Le = (slice: FileSlice) => {
+	checkIsInRange(slice, 4);
+
 	const value = slice.view.getUint32(slice.bufferPos, true);
 	slice.bufferPos += 4;
 
@@ -208,6 +236,8 @@ export const readU32Le = (slice: FileSlice) => {
 };
 
 export const readI32Be = (slice: FileSlice) => {
+	checkIsInRange(slice, 4);
+
 	const value = slice.view.getInt32(slice.bufferPos, false);
 	slice.bufferPos += 4;
 
@@ -215,6 +245,8 @@ export const readI32Be = (slice: FileSlice) => {
 };
 
 export const readI32Le = (slice: FileSlice) => {
+	checkIsInRange(slice, 4);
+
 	const value = slice.view.getInt32(slice.bufferPos, true);
 	slice.bufferPos += 4;
 
@@ -255,6 +287,8 @@ export const readI64Le = (slice: FileSlice) => {
 };
 
 export const readF32Be = (slice: FileSlice) => {
+	checkIsInRange(slice, 4);
+
 	const value = slice.view.getFloat32(slice.bufferPos, false);
 	slice.bufferPos += 4;
 
@@ -262,6 +296,8 @@ export const readF32Be = (slice: FileSlice) => {
 };
 
 export const readF64Be = (slice: FileSlice) => {
+	checkIsInRange(slice, 8);
+
 	const value = slice.view.getFloat64(slice.bufferPos, false);
 	slice.bufferPos += 8;
 
@@ -269,9 +305,7 @@ export const readF64Be = (slice: FileSlice) => {
 };
 
 export const readAscii = (slice: FileSlice, length: number) => {
-	if (slice.bufferPos + length > slice.bytes.length) {
-		throw new RangeError('Reading past end of slice.');
-	}
+	checkIsInRange(slice, length);
 
 	let str = '';
 
diff --git a/src/source.ts b/src/source.ts
index 37eaa43..594393a 100644
--- a/src/source.ts
+++ b/src/source.ts
@@ -764,6 +764,8 @@ export class StreamSource extends Source {
 			if (data instanceof Promise) data = await data;
 
 			if (data instanceof Uint8Array) {
+				data = toUint8Array(data); // Normalize things like Node.js Buffer to Uint8Array
+
 				if (data.length !== originalTargetPos - worker.currentPos) {
 					// Yes, we're that strict
 					throw new Error(
@@ -798,8 +800,10 @@ export class StreamSource extends Source {
 						throw new TypeError('ReadableStream returned by options.read must yield Uint8Array chunks.');
 					}
 
-					this.onread?.(worker.currentPos, worker.currentPos + value.length);
-					this._orchestrator.supplyWorkerData(worker, value);
+					const data = toUint8Array(value); // Normalize things like Node.js Buffer to Uint8Array
+
+					this.onread?.(worker.currentPos, worker.currentPos + data.length);
+					this._orchestrator.supplyWorkerData(worker, data);
 				}
 			} else {
 				throw new TypeError('options.read must return or resolve to a Uint8Array or a ReadableStream.');
diff --git a/src/wave/wave-demuxer.ts b/src/wave/wave-demuxer.ts
index 1b5bbe4..c552827 100644
--- a/src/wave/wave-demuxer.ts
+++ b/src/wave/wave-demuxer.ts
@@ -102,8 +102,12 @@ export class WaveDemuxer extends Demuxer {
 				} else if (chunkId === 'ds64') {
 					// File and data chunk sizes are defined in here instead
 
-					const riffChunkSize = readU64(slice, littleEndian);
-					dataChunkSize = readU64(slice, littleEndian);
+					let ds64Slice = this.reader.requestSlice(startPos, chunkSize);
+					if (ds64Slice instanceof Promise) ds64Slice = await ds64Slice;
+					if (!ds64Slice) break;
+
+					const riffChunkSize = readU64(ds64Slice, littleEndian);
+					dataChunkSize = readU64(ds64Slice, littleEndian);
 
 					totalFileSize = Math.min(riffChunkSize + 8, this.reader.fileSize ?? Infinity);
 				} else if (chunkId === 'LIST') {