diff --git a/src/cjs/browser.cjs b/src/cjs/browser.cjs
index f44586d..607fe23 100644
--- a/src/cjs/browser.cjs
+++ b/src/cjs/browser.cjs
@@ -12,7 +12,7 @@ const HEX_CODEPOINTS = Array(256)
     return index < 0 ? undefined : index < 16 ? index : index - 6;
 });
 const ENCODER = new TextEncoder();
-const DECODER = new TextDecoder("ascii");
+const DECODER = new TextDecoder();
 function toUtf8(bytes) {
     return DECODER.decode(bytes);
 }
diff --git a/src/mjs/browser.js b/src/mjs/browser.js
index e1909ae..89379f0 100644
--- a/src/mjs/browser.js
+++ b/src/mjs/browser.js
@@ -9,7 +9,7 @@ const HEX_CODEPOINTS = Array(256)
     return index < 0 ? undefined : index < 16 ? index : index - 6;
 });
 const ENCODER = new TextEncoder();
-const DECODER = new TextDecoder("ascii");
+const DECODER = new TextDecoder();
 export function toUtf8(bytes) {
     return DECODER.decode(bytes);
 }
diff --git a/ts_src/browser.ts b/ts_src/browser.ts
index 08e801c..57f5a5f 100644
--- a/ts_src/browser.ts
+++ b/ts_src/browser.ts
@@ -9,7 +9,7 @@ const HEX_CODEPOINTS: (number | undefined)[] = Array(256)
     return index < 0 ? undefined : index < 16 ? index : index - 6;
   });
 const ENCODER = new TextEncoder();
-const DECODER = new TextDecoder("ascii");
+const DECODER = new TextDecoder();
 
 export function toUtf8(bytes: Uint8Array): string {
   return DECODER.decode(bytes);
diff --git a/ts_src/tests.spec.ts b/ts_src/tests.spec.ts
index 5c6557e..427da31 100644
--- a/ts_src/tests.spec.ts
+++ b/ts_src/tests.spec.ts
@@ -18,6 +18,10 @@ const bytes3 = f([0x21, 0x7e]);
 const utf8 = "!~";
 const longBytes2 = new Uint8Array(513).fill(0x61);
 const longUtf8 = "a".repeat(513);
+const testBytes = f([
+  227, 129, 147, 227, 130, 147, 227, 129, 171, 227, 129, 161, 227, 129, 175,
+]);
+const str = "こんにちは";
 
 const brokenHexes = [
   [" ff00", f([]), "leading space"],
@@ -45,6 +49,7 @@ describe(`Uint8Array tools`, () => {
       });
       it(`should output utf8 with toUtf8`, () => {
         expect(tools.toUtf8(bytes3)).toEqual(utf8);
+        expect(tools.toUtf8(testBytes)).toEqual(str);
         expect(tools.toUtf8(longBytes2)).toEqual(longUtf8);
         expect((tools.toUtf8 as any)()).toEqual("");
       });