diff --git a/ext/bg/js/japanese.js b/ext/bg/js/japanese.js
index c74e4553..ac81acb5 100644
--- a/ext/bg/js/japanese.js
+++ b/ext/bg/js/japanese.js
@@ -124,25 +124,25 @@
         return wanakana.toRomaji(text);
     }
 
-    function convertReading(expressionFragment, readingFragment, readingMode) {
+    function convertReading(expression, reading, readingMode) {
         switch (readingMode) {
             case 'hiragana':
-                return convertKatakanaToHiragana(readingFragment);
+                return convertKatakanaToHiragana(reading);
             case 'katakana':
-                return convertHiraganaToKatakana(readingFragment);
+                return convertHiraganaToKatakana(reading);
             case 'romaji':
-                if (readingFragment) {
-                    return convertToRomaji(readingFragment);
+                if (reading) {
+                    return convertToRomaji(reading);
                 } else {
-                    if (isStringEntirelyKana(expressionFragment)) {
-                        return convertToRomaji(expressionFragment);
+                    if (isStringEntirelyKana(expression)) {
+                        return convertToRomaji(expression);
                     }
                 }
-                return readingFragment;
+                return reading;
             case 'none':
                 return '';
             default:
-                return readingFragment;
+                return reading;
         }
     }
 
diff --git a/test/test-japanese.js b/test/test-japanese.js
index 7fd71ba8..87efdfad 100644
--- a/test/test-japanese.js
+++ b/test/test-japanese.js
@@ -208,8 +208,8 @@ function testConvertReading() {
         [['有り難う', '', 'default'], '']
     ];
 
-    for (const [[expressionFragment, readingFragment, readingMode], expected] of data) {
-        assert.strictEqual(jp.convertReading(expressionFragment, readingFragment, readingMode), expected);
+    for (const [[expression, reading, readingMode], expected] of data) {
+        assert.strictEqual(jp.convertReading(expression, reading, readingMode), expected);
     }
 }