diff --git a/app/build.gradle b/app/build.gradle
index 87b76990..989c908c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -14,7 +14,7 @@ android {
         minSdkVersion 16
         targetSdkVersion 29
         versionCode 31
-        versionName "4.2-beta2"
+        versionName "4.2-beta2-hotfix1"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         multiDexEnabled true
         vectorDrawables.useSupportLibrary = true
@@ -25,7 +25,7 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
         }
         buildTypes.each {
-            it.buildConfigField('boolean', 'PRERELEASE', 'false')
+            it.buildConfigField('boolean', 'PRERELEASE', 'true')
             it.buildConfigField('boolean', 'CENSOR', 'false')
         }
     }
diff --git a/app/release/output.json b/app/release/output.json
index f833a508..4995868c 100644
--- a/app/release/output.json
+++ b/app/release/output.json
@@ -1 +1 @@
-[{"outputType":{"type":"APK"},"apkData":{"type":"MAIN","splits":[],"versionCode":31,"versionName":"4.2-beta2","enabled":true,"outputFile":"app-release.apk","fullName":"release","baseName":"release"},"path":"app-release.apk","properties":{}}]
\ No newline at end of file
+[{"outputType":{"type":"APK"},"apkData":{"type":"MAIN","splits":[],"versionCode":31,"versionName":"4.2-beta2-hotfix1","enabled":true,"outputFile":"app-release.apk","fullName":"release","baseName":"release"},"path":"app-release.apk","properties":{}}]
\ No newline at end of file
diff --git a/app/src/main/java/xyz/quaver/pupil/util/update.kt b/app/src/main/java/xyz/quaver/pupil/util/update.kt
index a9c98b55..c42c13d8 100644
--- a/app/src/main/java/xyz/quaver/pupil/util/update.kt
+++ b/app/src/main/java/xyz/quaver/pupil/util/update.kt
@@ -114,7 +114,8 @@ fun updateOldReaderGalleries(context: Context) {
        reader["code"] = when {
            (File(gallery, "images").list()?.
                all { !it.endsWith("webp") } ?: return@forEach) &&
-                   availableInHiyobi(gallery.name.toInt()) -> json.toJson(codeSerializer, Reader.Code.HIYOBI)
+                   availableInHiyobi(gallery.name.toIntOrNull() ?: return@forEach)
+                -> json.toJson(codeSerializer, Reader.Code.HIYOBI)
            else -> json.toJson(codeSerializer, Reader.Code.HITOMI)
        }