diff --git a/ext/bg/js/database.js b/ext/bg/js/database.js
index 400ebd6a..69a3bbdd 100644
--- a/ext/bg/js/database.js
+++ b/ext/bg/js/database.js
@@ -35,7 +35,7 @@ class Database {
     }
 
     prepare() {
-        if (!this.db) {
+        if (this.db) {
             return Promise.reject('database already initialized');
         }
 
diff --git a/ext/bg/js/translator.js b/ext/bg/js/translator.js
index 8d65a0cd..f1858247 100644
--- a/ext/bg/js/translator.js
+++ b/ext/bg/js/translator.js
@@ -53,7 +53,7 @@ class Translator {
         }
 
         return this.findTermsDeinflected(text, titles, cache).then(deinfLiteral => {
-            const textHiragana = wanakana._katakanaToHiragana(text);
+            const textHiragana = jpKatakanaToHiragana(text);
             if (text === textHiragana) {
                 return deinfLiteral;
             } else {
diff --git a/ext/bg/js/util.js b/ext/bg/js/util.js
index cdd5ec31..b39b4b2f 100644
--- a/ext/bg/js/util.js
+++ b/ext/bg/js/util.js
@@ -43,6 +43,10 @@ function jpIsKana(c) {
     return wanakana.isKana(c);
 }
 
+function jpKatakanaToHiragana(text) {
+    return wanakana._katakanaToHiragana(text);
+}
+
 
 /*
  * Commands