diff --git a/.gitignore b/.gitignore
index 4b550b45..77faf521 100644
--- a/.gitignore
+++ b/.gitignore
@@ -258,3 +258,4 @@ build-test-Desktop_x86_windows_msvc2019_pe_32bit-Debug
 test/vs2019/.vs
 Corel Auto-Preserve
 test/vs2019/Debug No Unit Tests
+test/kdevelopbuild
diff --git a/include/etl/variant_new.h b/include/etl/experimental/variant_new.h
similarity index 100%
rename from include/etl/variant_new.h
rename to include/etl/experimental/variant_new.h
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index caba0ea6..06121a05 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -173,7 +173,13 @@ add_executable(etl_tests
 
 if(UNIX AND NOT APPLE)
   # atomic is need on Linux with Clang
-  target_link_libraries(etl_tests UnitTest++ atomic)
+  set(THREADS_PREFER_PTHREAD_FLAG ON)
+  find_package(Threads REQUIRED)
+  target_link_libraries(etl_tests UnitTest++ atomic Threads::Threads)
+elseif(NOT UNIX AND APPLE)
+  set(THREADS_PREFER_PTHREAD_FLAG ON)
+  find_package(Threads REQUIRED)
+  target_link_libraries(etl_tests UnitTest++)
 else()
   target_link_libraries(etl_tests UnitTest++)
 endif()
diff --git a/test/codeblocks/ETL.cbp b/test/codeblocks/ETL.cbp
index 51483503..9d532038 100644
--- a/test/codeblocks/ETL.cbp
+++ b/test/codeblocks/ETL.cbp
@@ -63,6 +63,7 @@
 				</Compiler>
 				<Linker>
 					<Add option="-m32" />
+					<Add option="-lpthread" />
 				</Linker>
 				<ExtraCommands>
 					<Add after="${TARGET_OUTPUT_DIR}${TARGET_OUTPUT_BASENAME}" />
@@ -97,6 +98,9 @@
 					<Add option="-D_DEBUG" />
 					<Add option="-DETL_NO_STL" />
 				</Compiler>
+				<Linker>
+					<Add option="-lpthread" />
+				</Linker>
 				<ExtraCommands>
 					<Add after="${TARGET_OUTPUT_DIR}${TARGET_OUTPUT_BASENAME}" />
 					<Mode after="always" />
diff --git a/test/test_atomic_gcc_sync.cpp b/test/test_atomic_gcc_sync.cpp
index ec6cee80..67ad4e93 100644
--- a/test/test_atomic_gcc_sync.cpp
+++ b/test/test_atomic_gcc_sync.cpp
@@ -32,6 +32,9 @@ SOFTWARE.
 #include "etl/atomic/atomic_gcc_sync.h"
 
 #include <atomic>
+#include <thread>
+
+#define REALTIME_TEST 1
 
 namespace
 {
@@ -480,5 +483,44 @@ namespace
       CHECK_EQUAL(compare_expected, test_expected);
       CHECK_EQUAL(compare.load(), test.load());
     }
+
+    //=========================================================================
+    #if REALTIME_TEST
+    etl::atomic_int32_t atomic_value = 0U;
+    etl::atomic<int>    atomic_flag  = false;
+
+    void thread1()
+    {
+      while (!atomic_flag.load());
+
+      for (int i = 0; i < 10000000; ++i)
+      {
+        ++atomic_value;
+      }
+    }
+
+    void thread2()
+    {
+      while (!atomic_flag.load());
+
+      for (int i = 0; i < 10000000; ++i)
+      {
+        --atomic_value;
+      }
+    }
+
+    TEST(test_atomic_multi_thread)
+    {
+      std::thread t1(thread1);
+      std::thread t2(thread2);
+
+      atomic_flag.store(true);
+
+      t1.join();
+      t2.join();
+
+      CHECK_EQUAL(0, atomic_value.load());
+    }
+    #endif
   };
 }
diff --git a/test/test_atomic_std.cpp b/test/test_atomic_std.cpp
index d34d491d..ea98228b 100644
--- a/test/test_atomic_std.cpp
+++ b/test/test_atomic_std.cpp
@@ -32,6 +32,13 @@ SOFTWARE.
 #include "etl/atomic/atomic_std.h"
 
 #include <atomic>
+#include <thread>
+
+#if defined(ETL_TARGET_OS_WINDOWS)
+  #include <Windows.h>
+#endif
+
+#define REALTIME_TEST 1
 
 namespace
 {
@@ -480,5 +487,61 @@ namespace
       CHECK_EQUAL(compare_expected, test_expected);
       CHECK_EQUAL(compare.load(), test.load());
     }
+
+    //=========================================================================
+#if REALTIME_TEST
+
+#if defined(ETL_TARGET_OS_WINDOWS) // Only Windows priority is currently supported
+  #define RAISE_THREAD_PRIORITY  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST)
+  #define FIX_PROCESSOR_AFFINITY1 SetThreadAffinityMask(GetCurrentThread(), 1)
+  #define FIX_PROCESSOR_AFFINITY2 SetThreadAffinityMask(GetCurrentThread(), 2)
+#else
+  #define RAISE_THREAD_PRIORITY
+  #define FIX_PROCESSOR_AFFINITY1
+  #define FIX_PROCESSOR_AFFINITY2
+#endif
+
+    etl::atomic_int32_t atomic_value = 0U;
+    etl::atomic<int>    start = false;
+
+    void thread1()
+    {
+      RAISE_THREAD_PRIORITY;
+      FIX_PROCESSOR_AFFINITY1;
+
+      while (!start.load());
+
+      for (int i = 0; i < 10000000; ++i)
+      {
+        ++atomic_value;
+      }
+    }
+
+    void thread2()
+    {
+      RAISE_THREAD_PRIORITY;
+      FIX_PROCESSOR_AFFINITY2;
+
+      while (!start.load());
+
+      for (int i = 0; i < 10000000; ++i)
+      {
+        --atomic_value;
+      }
+    }
+
+    TEST(test_atomic_multi_thread)
+    {
+      std::thread t1(thread1);
+      std::thread t2(thread2);
+
+      start.store(true);
+
+      t1.join();
+      t2.join();
+
+      CHECK_EQUAL(0, atomic_value.load());
+    }
+#endif
   };
 }
diff --git a/test/test_callback_timer.cpp b/test/test_callback_timer.cpp
index 7a047e6c..8aeb924b 100644
--- a/test/test_callback_timer.cpp
+++ b/test/test_callback_timer.cpp
@@ -55,6 +55,7 @@ namespace
   public:
 
     Test()
+      : p_controller(nullptr)
     {
     }
 
@@ -684,7 +685,8 @@ namespace
     #define RAISE_THREAD_PRIORITY  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST)
     #define FIX_PROCESSOR_AFFINITY SetThreadAffinityMask(GetCurrentThread(), 1);
   #else
-    #error No thread priority modifier defined
+    #define RAISE_THREAD_PRIORITY
+    #define FIX_PROCESSOR_AFFINITY
   #endif
 
     etl::callback_timer<3> controller;
diff --git a/test/test_message_timer.cpp b/test/test_message_timer.cpp
index a5eb6b1f..064ba063 100644
--- a/test/test_message_timer.cpp
+++ b/test/test_message_timer.cpp
@@ -601,7 +601,8 @@ namespace
     #define RAISE_THREAD_PRIORITY  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST)
     #define FIX_PROCESSOR_AFFINITY SetThreadAffinityMask(GetCurrentThread(), 1);
   #else
-    #error No thread priority modifier defined
+    #define RAISE_THREAD_PRIORITY
+    #define FIX_PROCESSOR_AFFINITY
   #endif
 
     etl::message_timer<3> controller;
diff --git a/test/test_queue_mpmc_mutex.cpp b/test/test_queue_mpmc_mutex.cpp
index 8b48555a..ed7fb3fe 100644
--- a/test/test_queue_mpmc_mutex.cpp
+++ b/test/test_queue_mpmc_mutex.cpp
@@ -41,7 +41,7 @@ SOFTWARE.
 
 #if ETL_HAS_MUTEX
 
-#if defined(ETL_COMPILER_MICROSOFT)
+#if defined(ETL_TARGET_OS_WINDOWS)
   #include <Windows.h>
 #endif
 
diff --git a/test/test_queue_mpmc_mutex_small.cpp b/test/test_queue_mpmc_mutex_small.cpp
index 2042841f..01a1d131 100644
--- a/test/test_queue_mpmc_mutex_small.cpp
+++ b/test/test_queue_mpmc_mutex_small.cpp
@@ -41,7 +41,7 @@ SOFTWARE.
 
 #if ETL_HAS_MUTEX
 
-#if defined(ETL_COMPILER_MICROSOFT)
+#if defined(ETL_TARGET_OS_WINDOWS)
   #include <Windows.h>
 #endif
 
diff --git a/test/test_queue_spsc_atomic.cpp b/test/test_queue_spsc_atomic.cpp
index 4534487a..f961aa80 100644
--- a/test/test_queue_spsc_atomic.cpp
+++ b/test/test_queue_spsc_atomic.cpp
@@ -38,7 +38,7 @@ SOFTWARE.
 
 #if ETL_HAS_ATOMIC
 
-#if defined(ETL_COMPILER_MICROSOFT)
+#if defined(ETL_TARGET_OS_WINDOWS)
   #include <Windows.h>
 #endif
 
diff --git a/test/test_queue_spsc_atomic_small.cpp b/test/test_queue_spsc_atomic_small.cpp
index 1f050c98..4a8ccc1d 100644
--- a/test/test_queue_spsc_atomic_small.cpp
+++ b/test/test_queue_spsc_atomic_small.cpp
@@ -38,7 +38,7 @@ SOFTWARE.
 
 #if ETL_HAS_ATOMIC
 
-#if defined(ETL_COMPILER_MICROSOFT)
+#if defined(ETL_TARGET_OS_WINDOWS)
   #include <Windows.h>
 #endif
 
diff --git a/test/test_queue_spsc_isr.cpp b/test/test_queue_spsc_isr.cpp
index 269cf5e0..a3433af4 100644
--- a/test/test_queue_spsc_isr.cpp
+++ b/test/test_queue_spsc_isr.cpp
@@ -571,12 +571,13 @@ namespace
     }
 
     //*************************************************************************
-#if REALTIME_TEST && defined(ETL_COMPILER_MICROSOFT)
+#if REALTIME_TEST
   #if defined(ETL_TARGET_OS_WINDOWS) // Only Windows priority is currently supported
     #define RAISE_THREAD_PRIORITY  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST)
     #define FIX_PROCESSOR_AFFINITY SetThreadAffinityMask(GetCurrentThread(), 1);
   #else
-    #error No thread priority modifier defined
+    #define RAISE_THREAD_PRIORITY
+    #define FIX_PROCESSOR_AFFINITY
   #endif
 
     size_t ticks = 0;
diff --git a/test/test_queue_spsc_isr_small.cpp b/test/test_queue_spsc_isr_small.cpp
index 9a8efb5d..0dbc33f3 100644
--- a/test/test_queue_spsc_isr_small.cpp
+++ b/test/test_queue_spsc_isr_small.cpp
@@ -589,12 +589,13 @@ namespace
     }
 
     //*************************************************************************
-#if REALTIME_TEST && defined(ETL_COMPILER_MICROSOFT)
+#if REALTIME_TEST
   #if defined(ETL_TARGET_OS_WINDOWS) // Only Windows priority is currently supported
     #define RAISE_THREAD_PRIORITY  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST)
     #define FIX_PROCESSOR_AFFINITY SetThreadAffinityMask(GetCurrentThread(), 1);
   #else
-    #error No thread priority modifier defined
+    #define RAISE_THREAD_PRIORITY
+    #define FIX_PROCESSOR_AFFINITY
   #endif
 
     size_t ticks = 0;
diff --git a/test/test_queue_spsc_locked.cpp b/test/test_queue_spsc_locked.cpp
index ff07d575..c0e14308 100644
--- a/test/test_queue_spsc_locked.cpp
+++ b/test/test_queue_spsc_locked.cpp
@@ -574,12 +574,13 @@ namespace
     }
 
     //*************************************************************************
-#if REALTIME_TEST && defined(ETL_COMPILER_MICROSOFT)
+#if REALTIME_TEST
   #if defined(ETL_TARGET_OS_WINDOWS) // Only Windows priority is currently supported
     #define RAISE_THREAD_PRIORITY  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST)
     #define FIX_PROCESSOR_AFFINITY SetThreadAffinityMask(GetCurrentThread(), 1);
   #else
-    #error No thread priority modifier defined
+    #define RAISE_THREAD_PRIORITY
+    #define FIX_PROCESSOR_AFFINITY
   #endif
 
     size_t ticks = 0;
diff --git a/test/test_queue_spsc_locked_small.cpp b/test/test_queue_spsc_locked_small.cpp
index 6f58bd05..b8bdbb94 100644
--- a/test/test_queue_spsc_locked_small.cpp
+++ b/test/test_queue_spsc_locked_small.cpp
@@ -34,7 +34,7 @@ SOFTWARE.
 #include <mutex>
 #include <vector>
 
-#if defined(ETL_COMPILER_MICROSOFT)
+#if defined(ETL_TARGET_OS_WINDOWS)
 #include <Windows.h>
 #endif
 
@@ -591,12 +591,13 @@ namespace
     }
 
     //*************************************************************************
-#if REALTIME_TEST && defined(ETL_COMPILER_MICROSOFT)
-  #if defined(ETL_TARGET_OS_WINDOWS) // Only Windows priority is currently supported
+#if REALTIME_TEST
+#if defined(ETL_TARGET_OS_WINDOWS) // Only Windows priority is currently supported
     #define RAISE_THREAD_PRIORITY  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST)
     #define FIX_PROCESSOR_AFFINITY SetThreadAffinityMask(GetCurrentThread(), 1);
   #else
-    #error No thread priority modifier defined
+    #define RAISE_THREAD_PRIORITY
+    #define FIX_PROCESSOR_AFFINITY
   #endif
 
     size_t ticks = 0;