diff --git a/src/media-sink.ts b/src/media-sink.ts
index 01d82cf..6fd28b8 100644
--- a/src/media-sink.ts
+++ b/src/media-sink.ts
@@ -38,6 +38,7 @@ import {
 	isWebKit,
 	last,
 	mapAsyncGenerator,
+	missingWebCodecsClassMessage,
 	promiseWithResolvers,
 	removeItem,
 	Rotation,
@@ -1691,8 +1692,12 @@ export class VideoSampleSink extends BaseMediaSampleSink<VideoSample> {
 		onError: (error: unknown) => unknown,
 	) {
 		if (!(await this._track.canDecode())) {
+			if (typeof VideoDecoder === 'undefined') {
+				throw new Error(missingWebCodecsClassMessage('VideoDecoder'));
+			}
+
 			throw new Error(
-				'This video track cannot be decoded by this browser. Make sure to check decodability before using'
+				'This video track cannot be decoded in this environment. Make sure to check decodability before using'
 				+ ' a track.',
 			);
 		}
@@ -2426,8 +2431,12 @@ export class AudioSampleSink extends BaseMediaSampleSink<AudioSample> {
 		onError: (error: unknown) => unknown,
 	) {
 		if (!(await this._track.canDecode())) {
+			if (typeof AudioDecoder === 'undefined') {
+				throw new Error(missingWebCodecsClassMessage('AudioDecoder'));
+			}
+
 			throw new Error(
-				'This audio track cannot be decoded by this browser. Make sure to check decodability before using'
+				'This audio track cannot be decoded in this environment. Make sure to check decodability before using'
 				+ ' a track.',
 			);
 		}
diff --git a/src/media-source.ts b/src/media-source.ts
index 74bf8a7..c724b96 100644
--- a/src/media-source.ts
+++ b/src/media-source.ts
@@ -29,6 +29,7 @@ import {
 	clearIntervalUnthrottled,
 	floorToDivisor,
 	last,
+	missingWebCodecsClassMessage,
 	promiseWithResolvers,
 	roundToDivisor,
 	setInt24,
@@ -718,7 +719,7 @@ class VideoEncoderWrapper {
 
 			if (!selected) {
 				if (typeof VideoEncoder === 'undefined') {
-					throw new Error('VideoEncoder is not supported by this browser.');
+					throw new Error(missingWebCodecsClassMessage('VideoEncoder'));
 				}
 
 				// The candidates only differ in their rate control, so we describe them as one config with a
@@ -731,7 +732,7 @@ class VideoEncoderWrapper {
 				throw new Error(
 					`This specific encoder configuration (${firstConfig.codec}, ${rateControls.join(' / ')},`
 					+ ` ${firstConfig.width}x${firstConfig.height}, hardware acceleration:`
-					+ ` ${firstConfig.hardwareAcceleration ?? 'no-preference'}) is not supported by this browser.`
+					+ ` ${firstConfig.hardwareAcceleration ?? 'no-preference'}) is not supported in this environment.`
 					+ ` Consider using another codec or changing your video parameters.`,
 				);
 			}
@@ -1694,8 +1695,8 @@ export class MediaStreamVideoTrackSource extends VideoSource {
 				});
 			} else {
 				throw new Error(
-					'When no explicit frame rate is set, MediaStreamTrackProcessor is required; but it\'s not supported'
-					+ ' by this browser.',
+					'When no explicit frame rate is set, MediaStreamTrackProcessor is required; but it\'s not available'
+					+ ' in this environment.',
 				);
 			}
 		}
@@ -2210,7 +2211,7 @@ class AudioEncoderWrapper {
 				this.initPcmEncoder();
 			} else {
 				if (typeof AudioEncoder === 'undefined') {
-					throw new Error('AudioEncoder is not supported by this browser.');
+					throw new Error(missingWebCodecsClassMessage('AudioEncoder'));
 				}
 
 				let supported: boolean;
@@ -2226,7 +2227,8 @@ class AudioEncoderWrapper {
 					throw new Error(
 						`This specific encoder configuration (${encoderConfig.codec}, ${encoderConfig.bitrate} bps,`
 						+ ` ${encoderConfig.numberOfChannels} channels, ${encoderConfig.sampleRate} Hz) is not`
-						+ ` supported by this browser. Consider using another codec or changing your audio parameters.`,
+						+ ` supported in this environment. Consider using another codec or changing your`
+						+ ` audio parameters.`,
 					);
 				}
 
diff --git a/src/misc.ts b/src/misc.ts
index 60fea06..3b0d98a 100644
--- a/src/misc.ts
+++ b/src/misc.ts
@@ -721,6 +721,16 @@ export const getChromiumVersion = () => {
 	return chromiumVersionCache = Number(match[1]!);
 };
 
+export const missingWebCodecsClassMessage = (className: string) => {
+	if (typeof globalThis.isSecureContext !== 'undefined' && !globalThis.isSecureContext) {
+		// WebCodecs is not exposed in insecure contexts
+		return `${className} is not available in this environment; this may be because this page is running in an`
+			+ ` insecure context. Try serving your page over HTTPS or use localhost.`;
+	}
+
+	return `${className} is not available in this environment.`;
+};
+
 /**
  * T or a promise that resolves to T.
  * @group Miscellaneous
diff --git a/src/packet.ts b/src/packet.ts
index 36901f4..f345b5d 100644
--- a/src/packet.ts
+++ b/src/packet.ts
@@ -155,7 +155,7 @@ export class EncodedPacket {
 			throw new TypeError('Metadata-only packets cannot be converted to a video chunk.');
 		}
 		if (typeof EncodedVideoChunk === 'undefined') {
-			throw new Error('Your browser does not support EncodedVideoChunk.');
+			throw new Error('EncodedVideoChunk is not available in this environment.');
 		}
 
 		return new EncodedVideoChunk({
@@ -179,7 +179,7 @@ export class EncodedPacket {
 			throw new TypeError('Metadata-only packets cannot be converted to a video chunk.');
 		}
 		if (typeof EncodedVideoChunk === 'undefined') {
-			throw new Error('Your browser does not support EncodedVideoChunk.');
+			throw new Error('EncodedVideoChunk is not available in this environment.');
 		}
 
 		return new EncodedVideoChunk({
@@ -198,7 +198,7 @@ export class EncodedPacket {
 			throw new TypeError('Metadata-only packets cannot be converted to an audio chunk.');
 		}
 		if (typeof EncodedAudioChunk === 'undefined') {
-			throw new Error('Your browser does not support EncodedAudioChunk.');
+			throw new Error('EncodedAudioChunk is not available in this environment.');
 		}
 
 		return new EncodedAudioChunk({