diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index aab4c0a..40856ce 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -80,6 +80,10 @@ kotlin {
             implementation("io.ktor:ktor-client-okhttp:$ktorVersion")
         }
 
+        jvmTest.dependencies {
+            implementation(kotlin("reflect"))
+        }
+
 
         jsMain.dependencies {
             implementation("io.ktor:ktor-client-js:$ktorVersion")
diff --git a/app/src/commonMain/kotlin/it/vercruysse/lemmyapi/v0x19/datatypes/CommunityAggregates.kt b/app/src/commonMain/kotlin/it/vercruysse/lemmyapi/v0x19/datatypes/CommunityAggregates.kt
index 8269e8a..6674b82 100644
--- a/app/src/commonMain/kotlin/it/vercruysse/lemmyapi/v0x19/datatypes/CommunityAggregates.kt
+++ b/app/src/commonMain/kotlin/it/vercruysse/lemmyapi/v0x19/datatypes/CommunityAggregates.kt
@@ -13,5 +13,5 @@ data class CommunityAggregates(
     val users_active_week: Int,
     val users_active_month: Int,
     val users_active_half_year: Int,
-    val subscribers_local: Int?,
+    val subscribers_local: Int? = null,
 )
diff --git a/app/src/jvmTest/kotlin/DatatypesValidation.kt b/app/src/jvmTest/kotlin/DatatypesValidation.kt
new file mode 100644
index 0000000..6d4bfa3
--- /dev/null
+++ b/app/src/jvmTest/kotlin/DatatypesValidation.kt
@@ -0,0 +1,42 @@
+import java.io.BufferedReader
+import java.io.InputStream
+import java.io.InputStreamReader
+import kotlin.reflect.full.primaryConstructor
+import kotlin.test.Test
+import kotlin.test.fail
+
+class DatatypesValidation {
+    private val versions = listOf("v0x18", "v0x19")
+
+    @Test
+    fun `all datatypes that are nullable should also be optional`() {
+        versions.flatMap { getClasses(this.javaClass.classLoader, "it/vercruysse/lemmyapi/$it/datatypes") }
+            .forEach { clazz ->
+                val kClass = clazz.kotlin
+                if (kClass.isData) {
+                    val primaryConstructor = kClass.primaryConstructor
+                    primaryConstructor?.parameters?.forEach { parameter ->
+                        if (parameter.type.isMarkedNullable && !parameter.isOptional) {
+                            fail("Parameter ${parameter.name} of class ${clazz.name} is nullable but not optional")
+                        }
+                    }
+                }
+            }
+    }
+
+    @Throws(Exception::class)
+    private fun getClasses(cl: ClassLoader, pack: String): List<Class<*>> {
+        val dottedPackage = pack.replace("[/]".toRegex(), ".")
+        val classes: MutableList<Class<*>> = ArrayList()
+        val upackage = cl.getResource(pack)
+
+        val dis = BufferedReader(InputStreamReader(upackage?.getContent() as InputStream))
+        var line: String?
+        while ((dis.readLine().also { line = it }) != null) {
+            if (line!!.endsWith(".class")) {
+                classes.add(Class.forName(dottedPackage + "." + line!!.substring(0, line!!.lastIndexOf('.'))))
+            }
+        }
+        return classes
+    }
+}
diff --git a/gradle.properties b/gradle.properties
index 63f418b..a5e3c11 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -19,4 +19,4 @@ POM_DEVELOPER_URL=https://github.com/MV-GH
 
 POM_ARTIFACT_ID=lemmy-api
 GROUP=it.vercruysse.lemmyapi
-VERSION_NAME=0.2.4-SNAPSHOT
+VERSION_NAME=0.2.5-SNAPSHOT