diff --git a/observable-cache-service-api/src/main/java/com/github/aleksandermielczarek/observablecache/service/api/AbstractObservableCacheService.java b/observable-cache-service-api/src/main/java/com/github/aleksandermielczarek/observablecache/service/api/AbstractObservableCacheService.java
index f56a8a9..d22fec0 100644
--- a/observable-cache-service-api/src/main/java/com/github/aleksandermielczarek/observablecache/service/api/AbstractObservableCacheService.java
+++ b/observable-cache-service-api/src/main/java/com/github/aleksandermielczarek/observablecache/service/api/AbstractObservableCacheService.java
@@ -29,7 +29,7 @@ public AbstractObservableCacheService(T observableCache) {
         }
     }
 
-    public abstract String creatorClassImpl();
+    protected abstract String creatorClassImpl();
 
     public <T> T createObservableCacheService(Class<T> observableCacheServiceClass) {
         return observableCacheServiceCreator.createObservableCacheService(observableCacheServiceClass, observableCache);
diff --git a/observable-cache-service/src/main/java/com/github/aleksandermielczarek/observablecache/service/ObservableCacheService.java b/observable-cache-service/src/main/java/com/github/aleksandermielczarek/observablecache/service/ObservableCacheService.java
index 9d0e3e0..467ea8e 100644
--- a/observable-cache-service/src/main/java/com/github/aleksandermielczarek/observablecache/service/ObservableCacheService.java
+++ b/observable-cache-service/src/main/java/com/github/aleksandermielczarek/observablecache/service/ObservableCacheService.java
@@ -14,7 +14,7 @@ public ObservableCacheService(ObservableCache observableCache) {
     }
 
     @Override
-    public String creatorClassImpl() {
+    protected String creatorClassImpl() {
         return "com.github.aleksandermielczarek.observablecache.service.ObservableCacheServiceCreatorImpl";
     }