diff --git a/dev/demux.html b/dev/demux.html
index 8391087..3bfb4db 100644
--- a/dev/demux.html
+++ b/dev/demux.html
@@ -22,7 +22,7 @@
 		for await (const packet of sink.packets()) {
 			console.log(packet);
 
-			if (packet.timestamp > 135) break;
+			//if (packet.timestamp > 135) break;
 		}
 
 		/*
diff --git a/package-lock.json b/package-lock.json
index ed9eeb2..f07e527 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "mediabunny",
-  "version": "1.9.2",
+  "version": "1.9.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "mediabunny",
-      "version": "1.9.2",
+      "version": "1.9.3",
       "license": "MPL-2.0",
       "workspaces": [
         "packages/*"
@@ -5900,9 +5900,9 @@
       }
     },
     "node_modules/mediabunny": {
-      "version": "1.9.1",
-      "resolved": "https://registry.npmjs.org/mediabunny/-/mediabunny-1.9.1.tgz",
-      "integrity": "sha512-DghqcYW2s8LsZ9kErFeZdm6308BEABYs8SkY1z3Y7v3LWgPNvBmkXk7Yt+EKcpEGEFjGgDGoTapOjrrrNh7dQA==",
+      "version": "1.9.2",
+      "resolved": "https://registry.npmjs.org/mediabunny/-/mediabunny-1.9.2.tgz",
+      "integrity": "sha512-U3RKZVvU2O7vXVtPf6Q+4XNulkV6fdVOVYMm7V2YTr6PqyqrvUl1eUCTtcrmQESgRi9sFZeXkUR8ln5TS48M2g==",
       "license": "MPL-2.0",
       "peer": true,
       "workspaces": [
@@ -9017,7 +9017,7 @@
     },
     "packages/mp3-encoder": {
       "name": "@mediabunny/mp3-encoder",
-      "version": "1.9.2",
+      "version": "1.9.3",
       "license": "MPL-2.0",
       "devDependencies": {
         "@types/emscripten": "^1.40.1"
diff --git a/package.json b/package.json
index b49df22..d0541fb 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "mediabunny",
   "author": "Vanilagy",
-  "version": "1.9.2",
+  "version": "1.9.3",
   "description": "Pure TypeScript media toolkit for reading, writing, and converting media files, directly in the browser.",
   "type": "module",
   "workspaces": [
diff --git a/packages/mp3-encoder/package.json b/packages/mp3-encoder/package.json
index f2de19e..883ca3c 100644
--- a/packages/mp3-encoder/package.json
+++ b/packages/mp3-encoder/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@mediabunny/mp3-encoder",
   "author": "Vanilagy",
-  "version": "1.9.2",
+  "version": "1.9.3",
   "description": "MP3 encoder extension for Mediabunny, based on LAME.",
   "main": "./dist/bundles/mediabunny-mp3-encoder.mjs",
   "module": "./dist/bundles/mediabunny-mp3-encoder.mjs",
diff --git a/src/isobmff/isobmff-demuxer.ts b/src/isobmff/isobmff-demuxer.ts
index 0f6c7cb..9a88c43 100644
--- a/src/isobmff/isobmff-demuxer.ts
+++ b/src/isobmff/isobmff-demuxer.ts
@@ -257,6 +257,9 @@ export class IsobmffDemuxer extends Demuxer {
 				);
 				const startPos = this.metadataReader.pos;
 				const boxInfo = this.metadataReader.readBoxHeader();
+				if (!boxInfo) {
+					break;
+				}
 
 				if (boxInfo.name === 'ftyp') {
 					const majorBrand = this.metadataReader.readAscii(4);
@@ -298,7 +301,7 @@ export class IsobmffDemuxer extends Demuxer {
 					this.metadataReader.pos = potentialMfraPos;
 					const boxInfo = this.metadataReader.readBoxHeader();
 
-					if (boxInfo.name === 'mfra') {
+					if (boxInfo && boxInfo.name === 'mfra') {
 						// We found the mfra box, allowing for much better random access. Let's parse it.
 
 						await this.metadataReader.reader.loadRange(
@@ -462,7 +465,7 @@ export class IsobmffDemuxer extends Demuxer {
 		);
 
 		const moofBoxInfo = this.metadataReader.readBoxHeader();
-		assert(moofBoxInfo.name === 'moof');
+		assert(moofBoxInfo?.name === 'moof');
 
 		const contentStart = this.metadataReader.pos;
 		await this.metadataReader.reader.loadRange(contentStart, contentStart + moofBoxInfo.contentSize);
@@ -508,7 +511,7 @@ export class IsobmffDemuxer extends Demuxer {
 
 			let nextFragmentIsFirstFragment = this.metadataReader.pos === 0;
 
-			while (this.metadataReader.pos < startPos) {
+			while (this.metadataReader.pos <= startPos - MIN_BOX_HEADER_SIZE) {
 				if (currentFragment?.nextFragment) {
 					currentFragment = currentFragment.nextFragment;
 					this.metadataReader.pos = currentFragment.moofOffset + currentFragment.moofSize;
@@ -519,6 +522,9 @@ export class IsobmffDemuxer extends Demuxer {
 					);
 					const startPos = this.metadataReader.pos;
 					const boxInfo = this.metadataReader.readBoxHeader();
+					if (!boxInfo) {
+						break;
+					}
 
 					if (boxInfo.name === 'moof') {
 						const index = binarySearchExact(this.fragments, startPos, x => x.moofOffset);
@@ -568,13 +574,21 @@ export class IsobmffDemuxer extends Demuxer {
 		const startIndex = this.metadataReader.pos;
 
 		while (this.metadataReader.pos - startIndex <= totalSize - MIN_BOX_HEADER_SIZE) {
-			this.traverseBox();
+			const foundBox = this.traverseBox();
+
+			if (!foundBox) {
+				break;
+			}
 		}
 	}
 
 	traverseBox() {
 		const startPos = this.metadataReader.pos;
 		const boxInfo = this.metadataReader.readBoxHeader();
+		if (!boxInfo) {
+			return false;
+		}
+
 		const boxEndPos = startPos + boxInfo.totalSize;
 
 		switch (boxInfo.name) {
@@ -825,6 +839,10 @@ export class IsobmffDemuxer extends Demuxer {
 				for (let i = 0; i < entries; i++) {
 					const startPos = this.metadataReader.pos;
 					const sampleBoxInfo = this.metadataReader.readBoxHeader();
+					if (!sampleBoxInfo) {
+						break;
+					}
+
 					const lowercaseBoxName = sampleBoxInfo.name.toLowerCase();
 
 					if (track.info.type === 'video') {
@@ -1904,6 +1922,7 @@ export class IsobmffDemuxer extends Demuxer {
 		}
 
 		this.metadataReader.pos = boxEndPos;
+		return true;
 	}
 }
 
@@ -2324,8 +2343,12 @@ abstract class IsobmffTrackBacking implements InputTrackBacking {
 
 	/** Looks for a packet in the fragments while trying to load as few fragments as possible to retrieve it. */
 	private async performFragmentedLookup(
+		// This function returns the best-matching sample that is currently loaded. Based on this information, we know
+		// which fragments we need to load to find the actual match.
 		getBestMatch: () => { fragmentIndex: number; sampleIndex: number; correctSampleFound: boolean },
+		// The timestamp with which we can search the lookup table
 		searchTimestamp: number,
+		// The timestamp for which we know the correct sample will not come after it
 		latestTimestamp: number,
 		options: PacketRetrievalOptions,
 	): Promise<EncodedPacket | null> {
@@ -2397,6 +2420,9 @@ abstract class IsobmffTrackBacking implements InputTrackBacking {
 				await metadataReader.reader.loadRange(metadataReader.pos, metadataReader.pos + MAX_BOX_HEADER_SIZE);
 				const startPos = metadataReader.pos;
 				const boxInfo = metadataReader.readBoxHeader();
+				if (!boxInfo) {
+					break;
+				}
 
 				if (boxInfo.name === 'moof') {
 					const index = binarySearchExact(demuxer.fragments, startPos, x => x.moofOffset);
diff --git a/src/isobmff/isobmff-reader.ts b/src/isobmff/isobmff-reader.ts
index 425059b..bbcd541 100644
--- a/src/isobmff/isobmff-reader.ts
+++ b/src/isobmff/isobmff-reader.ts
@@ -132,6 +132,11 @@ export class IsobmffReader {
 			headerSize = 16;
 		}
 
-		return { name, totalSize, headerSize, contentSize: totalSize - headerSize };
+		const contentSize = totalSize - headerSize;
+		if (contentSize < 0) {
+			return null; // Hardly a box is it
+		}
+
+		return { name, totalSize, headerSize, contentSize };
 	}
 }
diff --git a/src/matroska/matroska-demuxer.ts b/src/matroska/matroska-demuxer.ts
index bb6f7ae..46632cd 100644
--- a/src/matroska/matroska-demuxer.ts
+++ b/src/matroska/matroska-demuxer.ts
@@ -760,6 +760,7 @@ export class MatroskaDemuxer extends Demuxer {
 
 		while (reader.pos - startIndex <= totalSize - MIN_HEADER_SIZE) {
 			const foundElement = this.traverseElement(reader);
+
 			if (!foundElement) {
 				break;
 			}