diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 4cc23cf52..d9dd971be 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -250,10 +250,9 @@ apply from: "$rootDir/common.gradle"
 | `extName`        | The name of the extension. Should be romanized if site name is not in English.                                                                                                         |
 | `extClass`       | Points to the class that implements `Source`. You can use a relative path starting with a dot (the package name is the base path). This is used to find and instantiate the source(s). |
 | `extVersionCode` | The extension version code. This must be a positive integer and incremented with any change to the code.                                                                               |
-| `libVersion`     | (Optional, defaults to `1.4`) The version of the [extensions library](https://github.com/tachiyomiorg/extensions-lib) used.                                                            |
 | `isNsfw`         | (Optional, defaults to `false`) Flag to indicate that a source contains NSFW content.                                                                                                  |
 
-The extension's version name is generated automatically by concatenating `libVersion` and `extVersionCode`.
+The extension's version name is generated automatically by concatenating `1.4` and `extVersionCode`.
 With the example used above, the version would be `1.4.1`.
 
 ### Core dependencies
diff --git a/common.gradle b/common.gradle
index 885a68660..2a5d1a6f6 100644
--- a/common.gradle
+++ b/common.gradle
@@ -3,6 +3,9 @@ apply plugin: 'kotlin-android'
 apply plugin: 'kotlinx-serialization'
 apply plugin: 'org.jmailen.kotlinter'
 
+assert !ext.has("pkgNameSuffix")
+assert !ext.has("libVersion")
+
 android {
     compileSdk AndroidConfig.compileSdk
 
@@ -21,14 +24,15 @@ android {
         targetSdk AndroidConfig.targetSdk
         applicationIdSuffix project.parent.name + "." + project.name
         versionCode extVersionCode
-        versionName project.ext.properties.getOrDefault("libVersion", "1.4") + ".$extVersionCode"
+        versionName "1.4.$versionCode"
         base {
             archivesName = "tachiyomi-$applicationIdSuffix-v$versionName"
         }
+        assert extClass.startsWith(".")
         manifestPlaceholders = [
                 appName : "Tachiyomi: $extName",
                 extClass: extClass,
-                nsfw: project.ext.properties.getOrDefault("isNsfw", false) ? 1 : 0,
+                nsfw: ext.find("isNsfw") ? 1 : 0,
         ]
     }