diff --git a/fairmq/devices/GenericFileSink.h b/fairmq/devices/GenericFileSink.h
index 938ef175..04b2c977 100644
--- a/fairmq/devices/GenericFileSink.h
+++ b/fairmq/devices/GenericFileSink.h
@@ -41,6 +41,7 @@
 template <typename T, typename U>
 class GenericFileSink : public FairMQDevice, public T, public U
 {
+  protected:
     typedef T                        deserialization_type;
     typedef U                                   sink_type;
   public:
diff --git a/fairmq/devices/GenericProcessor.h b/fairmq/devices/GenericProcessor.h
index 11e79c87..aab94d32 100644
--- a/fairmq/devices/GenericProcessor.h
+++ b/fairmq/devices/GenericProcessor.h
@@ -43,6 +43,7 @@
 template <typename T, typename U, typename V>
 class GenericProcessor : public FairMQDevice, public T, public U, public V
 {
+  protected:
     typedef T                                         deserialization_type;
     typedef U                                           serialization_type;
     typedef V                                               proc_task_type;
diff --git a/fairmq/devices/GenericSampler.h b/fairmq/devices/GenericSampler.h
index edb49855..a6ae6656 100644
--- a/fairmq/devices/GenericSampler.h
+++ b/fairmq/devices/GenericSampler.h
@@ -56,6 +56,7 @@
 template <typename T, typename U, typename K, typename L>
 class base_GenericSampler : public FairMQDevice, public T, public U
 {
+  protected:
     typedef T                                                 source_type;
     typedef U                                          serialization_type;
     typedef K                                                    key_type;