diff --git a/index.js b/index.js
index 9770ad8..788df02 100644
--- a/index.js
+++ b/index.js
@@ -39,12 +39,13 @@ const getStreamContents = async (stream, {convertChunk, getSize, getContents}, {
 		for await (const chunk of stream) {
 			const chunkType = getChunkType(chunk);
 			const convertedChunk = convertChunk[chunkType](chunk, textDecoder);
-			length += getSize(convertedChunk);
+			const chunkSize = getSize(convertedChunk);
 
-			if (length > maxBuffer) {
+			if (length + chunkSize > maxBuffer) {
 				throw new MaxBufferError();
 			}
 
+			length += chunkSize;
 			chunks.push(convertedChunk);
 		}
 
diff --git a/test.js b/test.js
index 20a7ded..c00507e 100644
--- a/test.js
+++ b/test.js
@@ -211,8 +211,8 @@ test('maxBuffer unit is each array element with getStreamAsArray()', checkMaxBuf
 
 test('set error.bufferedData when `maxBuffer` is hit', async t => {
 	const maxBuffer = fixtureLength - 1;
-	const {bufferedData} = await t.throwsAsync(setup([...fixtureString], {maxBuffer}), {instanceOf: MaxBufferError});
-	t.true(fixtureString.startsWith(bufferedData));
+	const {bufferedData} = await t.throwsAsync(setupBuffer([...fixtureString], {maxBuffer}), {instanceOf: MaxBufferError});
+	t.true(fixtureString.startsWith(bufferedData.toString()));
 	t.true(bufferedData.length <= maxBuffer);
 });