diff --git a/include/etl/timer.h b/include/etl/timer.h
index c3ce017b..681180c3 100644
--- a/include/etl/timer.h
+++ b/include/etl/timer.h
@@ -142,24 +142,42 @@ namespace etl
 #endif
 
     // Timer owner.
-    struct owner
-    {
-      typedef void* type;
-
 #if ETL_USING_CPP11
-      static ETL_CONSTANT type No_Owner = ETL_NULLPTR;
+    namespace private_timer
+    {
+      template <typename TDummy>
+      struct owner_static
+      {
+        using type = const void*;
+        static constexpr type No_Owner = nullptr;
+      };
+
+      template <typename TDummy>
+      constexpr typename owner_static<TDummy>::type owner_static<TDummy>::No_Owner;
+    } // namespace private_timer
 #else
-      static ETL_CONSTANT type No_Owner;
+    namespace private_timer
+    {
+      template <typename TDummy>
+      struct owner_static
+      {
+        typedef const void* type;
+
+        static const type No_Owner;
+      };
+
+      template <typename TDummy>
+      const typename owner_static<TDummy>::type owner_static<TDummy>::No_Owner = ETL_NULLPTR;
+    }
 #endif
+
+    struct owner : private_timer::owner_static<void>
+    {
     };
 
 #if ETL_USING_CPP11
     using owner_t = owner::type;
 #endif
-
-#if ETL_NOT_USING_CPP11
-    owner::type const owner::No_Owner = ETL_NULLPTR;
-#endif
   } // namespace timer
 } // namespace etl
 
diff --git a/include/etl/timer_lock_policy.h b/include/etl/timer_lock_policy.h
index 11927f3d..534083f5 100644
--- a/include/etl/timer_lock_policy.h
+++ b/include/etl/timer_lock_policy.h
@@ -97,7 +97,8 @@ namespace etl
 
       etl::atomic_bool lock_flag;
     };
+#endif
   }
 }
-#endif
+
 #endif
diff --git a/include/etl/timer_node.h b/include/etl/timer_node.h
index 8bbac3c3..a5924fbb 100644
--- a/include/etl/timer_node.h
+++ b/include/etl/timer_node.h
@@ -289,7 +289,7 @@ namespace etl
       node*                      registered_next; ///< The next timer in the registered timer list. unlinked() if the timer is not registered.
       node*                      active_next;     ///< The next timer in the active timer list. unlinked() if the timer is not active.
       node*                      expired_next;    ///< The next timer in the expired timer list. unlinked() if the timer is not expired.
-      void*                      owner;           ///< The owner of the timer.
+      const void*                owner;           ///< The owner of the timer.
       etl::timer::config         config;          ///< The configuration of the timer.
       etl::timer::interval::type delta;           ///< The time remaining until the timer expires.
     };
diff --git a/include/etl/timer_notifications.h b/include/etl/timer_notifications.h
deleted file mode 100644
index 54886cab..00000000
--- a/include/etl/timer_notifications.h
+++ /dev/null
@@ -1,59 +0,0 @@
-/******************************************************************************
-The MIT License(MIT)
-
-Embedded Template Library.
-https://github.com/ETLCPP/etl
-https://www.etlcpp.com
-
-Copyright(c) 2017 John Wellbelove
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files(the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions :
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
-******************************************************************************/
-
-#ifndef ETL_TIMER_NOTIFICATION_INCLUDED
-#define ETL_TIMER_NOTIFICATION_INCLUDED
-
-#include "platform.h"
-
-//*****************************************************************************
-// Definitions common to timers.
-//*****************************************************************************
-
-namespace etl
-{
-  namespace timer
-  {
-    //***************************************************************************
-    /// Default class for time to next notification
-    //***************************************************************************
-    class timer_time_to_next_notification
-    {
-    public:
-
-      virtual ~timer_time_to_next_notification() ETL_NOEXCEPT {}
-
-      virtual void invoke(uint32_t)
-      {
-        // Do nothing by default.
-      }
-    };
-  }; // namespace timer
-} // namespace etl
-
-#endif