diff --git a/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/FlowPersistenceImpl.kt b/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/FlowPersistenceImpl.kt
index 4ad3115c03..e99fbe013b 100644
--- a/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/FlowPersistenceImpl.kt
+++ b/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/FlowPersistenceImpl.kt
@@ -5,7 +5,7 @@ import com.russhwolf.settings.coroutines.FlowSettings
 import kotlinx.coroutines.flow.Flow
 
 @Suppress("OPT_IN_USAGE")
-class FlowPersistenceImpl(private val flowSettings: FlowSettings) : FlowPersistence {
+internal class FlowPersistenceImpl(private val flowSettings: FlowSettings) : FlowPersistence {
     @Suppress("UNCHECKED_CAST")
     override fun <T : Any> getFlow(key: String, defaultValue: T): Flow<T> =
         when (defaultValue) {
diff --git a/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/SuspendPersistenceImpl.kt b/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/SuspendPersistenceImpl.kt
index 80cda13286..9c905f492e 100644
--- a/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/SuspendPersistenceImpl.kt
+++ b/client/core/persistence/src/commonMain/kotlin/com/oztechan/ccc/client/core/persistence/SuspendPersistenceImpl.kt
@@ -4,7 +4,8 @@ import com.oztechan.ccc.client.core.persistence.error.UnsupportedPersistenceExce
 import com.russhwolf.settings.coroutines.SuspendSettings
 
 @Suppress("OPT_IN_USAGE")
-class SuspendPersistenceImpl(private val suspendSettings: SuspendSettings) : SuspendPersistence {
+internal class SuspendPersistenceImpl(private val suspendSettings: SuspendSettings) :
+    SuspendPersistence {
 
     @Suppress("UNCHECKED_CAST")
     override suspend fun <T : Any> getSuspend(key: String, defaultValue: T): T =
diff --git a/client/storage/calculation/src/commonMain/kotlin/com/oztechan/ccc/client/storage/calculation/CalculationStorageImpl.kt b/client/storage/calculation/src/commonMain/kotlin/com/oztechan/ccc/client/storage/calculation/CalculationStorageImpl.kt
index 2d5203317b..0b4c158741 100644
--- a/client/storage/calculation/src/commonMain/kotlin/com/oztechan/ccc/client/storage/calculation/CalculationStorageImpl.kt
+++ b/client/storage/calculation/src/commonMain/kotlin/com/oztechan/ccc/client/storage/calculation/CalculationStorageImpl.kt
@@ -2,7 +2,7 @@ package com.oztechan.ccc.client.storage.calculation
 
 import com.oztechan.ccc.client.core.persistence.SuspendPersistence
 
-class CalculationStorageImpl(
+internal class CalculationStorageImpl(
     private val suspendPersistence: SuspendPersistence
 ) : CalculationStorage {
 
diff --git a/test/src/test/kotlin/com/oztechan/ccc/test/ConventionTest.kt b/test/src/test/kotlin/com/oztechan/ccc/test/ConventionTest.kt
index 4ba38480a4..0bc328f821 100644
--- a/test/src/test/kotlin/com/oztechan/ccc/test/ConventionTest.kt
+++ b/test/src/test/kotlin/com/oztechan/ccc/test/ConventionTest.kt
@@ -6,6 +6,7 @@ import com.lemonappdev.konsist.api.declaration.KoFunctionDeclaration
 import com.lemonappdev.konsist.api.declaration.KoPropertyDeclaration
 import com.lemonappdev.konsist.api.ext.list.indexOfFirstInstance
 import com.lemonappdev.konsist.api.ext.list.indexOfLastInstance
+import com.lemonappdev.konsist.api.ext.list.withNameEndingWith
 import com.lemonappdev.konsist.api.verify.assertFalse
 import com.lemonappdev.konsist.api.verify.assertTrue
 import org.junit.Test
@@ -106,4 +107,13 @@ internal class ConventionTest {
                 }
             }
     }
+
+    @Test
+    fun `Impl classes should be internal`() {
+        Konsist
+            .scopeFromProject()
+            .classes()
+            .withNameEndingWith("Impl")
+            .assertTrue { it.hasInternalModifier }
+    }
 }