diff --git a/src/Encoder/Encoder.php b/src/Encoder/Encoder.php
index c363953..2e2ac79 100644
--- a/src/Encoder/Encoder.php
+++ b/src/Encoder/Encoder.php
@@ -115,7 +115,11 @@ public static function encode(
         $headerAndDataBits->appendBitArray($headerBits);
 
         // Find "length" of main segment and write it.
-        $numLetters = (Mode::BYTE() === $mode ? $dataBits->getSizeInBytes() : strlen($content));
+        $numLetters = match ($mode) {
+            Mode::BYTE()                          => $dataBits->getSizeInBytes(),
+            Mode::NUMERIC(), Mode::ALPHANUMERIC() => strlen($content),
+            Mode::KANJI()                         => iconv_strlen($content, 'utf-8'),
+        };
         self::appendLengthInfo($numLetters, $version, $mode, $headerAndDataBits);
 
         // Put data together into the overall payload.
@@ -514,31 +518,15 @@ private static function appendLengthInfo(int $numLetters, Version $version, Mode
 
     /**
      * Appends bytes to a bit array in a specific mode.
-     *
-     * @throws WriterException if an invalid mode was supplied
      */
     private static function appendBytes(string $content, Mode $mode, BitArray $bits, string $encoding) : void
     {
-        switch ($mode) {
-            case Mode::NUMERIC():
-                self::appendNumericBytes($content, $bits);
-                break;
-
-            case Mode::ALPHANUMERIC():
-                self::appendAlphanumericBytes($content, $bits);
-                break;
-
-            case Mode::BYTE():
-                self::append8BitBytes($content, $bits, $encoding);
-                break;
-
-            case Mode::KANJI():
-                self::appendKanjiBytes($content, $bits);
-                break;
-
-            default:
-                throw new WriterException('Invalid mode: ' . $mode);
-        }
+        match ($mode) {
+            Mode::NUMERIC()      => self::appendNumericBytes($content, $bits),
+            Mode::ALPHANUMERIC() => self::appendAlphanumericBytes($content, $bits),
+            Mode::BYTE()         => self::append8BitBytes($content, $bits, $encoding),
+            Mode::KANJI()        => self::appendKanjiBytes($content, $bits),
+        };
     }
 
     /**
diff --git a/test/Encoder/EncoderTest.php b/test/Encoder/EncoderTest.php
index 66459e9..26d1ab1 100644
--- a/test/Encoder/EncoderTest.php
+++ b/test/Encoder/EncoderTest.php
@@ -87,6 +87,12 @@ public function testChooseMode() : void
 
         // Sou-Utso-Byou in Kanji in SHIFT-JIS
         $this->assertSame(Mode::BYTE(), $this->methods['chooseMode']->invoke(null, "\xe\x4\x9\x5\x9\x61"));
+
+        // SHIFT-JIS encoding, content only consists of double-byte kanji characters
+        $this->assertSame(Mode::KANJI(), $this->methods['chooseMode']->invoke(null, 'あいうえお', 'SHIFT-JIS'));
+
+        // SHIFT-JIS encoding, but content doesn't exclusively consist of kanji characters
+        $this->assertSame(Mode::BYTE(), $this->methods['chooseMode']->invoke(null, 'あいうえお123', 'SHIFT-JIS'));
     }
 
     public function testEncode() : void