@@ -274,11 +274,13 @@ function ZlibBase(opts, mode, handle, { flush, finishFlush, fullFlush }) {
       );
     }
 
-    if (opts.encoding || opts.objectMode || opts.writableObjectMode) {
+    if (opts.encoding || opts.objectMode || opts.writableObjectMode ||
+          opts.decodeStrings === false) {
       opts = { ...opts };
       opts.encoding = null;
       opts.objectMode = false;
       opts.writableObjectMode = false;
+      opts.decodeStrings = true;
     }
   }
 
 
@@ -0,0 +1,32 @@
+'use strict';
+
+// Strings must be decoded before they reach the native handle, even when
+// decodeStrings: false is passed. This used to abort the process.
+
+const common = require('../common');
+const assert = require('assert');
+const zlib = require('zlib');
+
+const input = 'héllo wörld';
+
+const pairs = [
+  [zlib.createGzip, zlib.gunzipSync],
+  [zlib.createDeflate, zlib.inflateSync],
+  [zlib.createDeflateRaw, zlib.inflateRawSync],
+  [zlib.createBrotliCompress, zlib.brotliDecompressSync],
+  [zlib.createZstdCompress, zlib.zstdDecompressSync],
+];
+
+for (const [createCompress, decompressSync] of pairs) {
+  const compress = createCompress({ decodeStrings: false });
+  const chunks = [];
+  compress.on('data', (chunk) => chunks.push(chunk));
+  compress.on('end', common.mustCall(() => {
+    assert.strictEqual(decompressSync(Buffer.concat(chunks)).toString(), input);
+  }));
+  compress.end(input);
+}
+
+zlib.gzip(input, { decodeStrings: false }, common.mustSucceed((compressed) => {
+  assert.strictEqual(zlib.gunzipSync(compressed).toString(), input);
+}));
Original file line number	Diff line number	Diff line change
`@@ -274,11 +274,13 @@ function ZlibBase(opts, mode, handle, { flush, finishFlush, fullFlush }) {`
`274`	`274`	`);`
`275`	`275`	`}`
`276`	`276`
`277`		`- if (opts.encoding \|\| opts.objectMode \|\| opts.writableObjectMode) {`
	`277`	`+ if (opts.encoding \|\| opts.objectMode \|\| opts.writableObjectMode \|\|`
	`278`	`+ opts.decodeStrings === false) {`
`278`	`279`	`opts = { ...opts };`
`279`	`280`	`opts.encoding = null;`
`280`	`281`	`opts.objectMode = false;`
`281`	`282`	`opts.writableObjectMode = false;`
	`283`	`+ opts.decodeStrings = true;`
`282`	`284`	`}`
`283`	`285`	`}`
`284`	`286`