diff --git a/Foundation/include/Poco/Mutex.h b/Foundation/include/Poco/Mutex.h
index 5070ab37a..b6f84aa56 100644
--- a/Foundation/include/Poco/Mutex.h
+++ b/Foundation/include/Poco/Mutex.h
@@ -22,16 +22,7 @@
 #include "Poco/Exception.h"
 #include "Poco/ScopedLock.h"
 #include "Poco/Timestamp.h"
-
-#if __cplusplus >= 201103L
-	#ifndef POCO_HAVE_STD_ATOMICS
-		#define POCO_HAVE_STD_ATOMICS
-	#endif
-#endif
-
-#ifdef POCO_HAVE_STD_ATOMICS
-	#include <atomic>
-#endif
+#include <atomic>
 
 
 #if defined(POCO_OS_FAMILY_WINDOWS)
@@ -161,8 +152,6 @@ private:
 };
 
 
-#ifdef POCO_HAVE_STD_ATOMICS
-
 class Foundation_API SpinlockMutex
 	/// A SpinlockMutex, implemented in terms of std::atomic_flag, as
 	/// busy-wait mutual exclusion.
@@ -210,8 +199,6 @@ private:
 	std::atomic_flag _flag = ATOMIC_FLAG_INIT;
 };
 
-#endif // POCO_HAVE_STD_ATOMICS
-
 
 class Foundation_API NullMutex
 	/// A NullMutex is an empty mutex implementation
@@ -336,8 +323,6 @@ inline void FastMutex::unlock()
 }
 
 
-#ifdef POCO_HAVE_STD_ATOMICS
-
 //
 // SpinlockMutex
 //
@@ -382,8 +367,6 @@ inline void SpinlockMutex::unlock()
 	_flag.clear(std::memory_order_release);
 }
 
-#endif // POCO_HAVE_STD_ATOMICS
-
 
 } // namespace Poco
 
diff --git a/Foundation/src/Mutex.cpp b/Foundation/src/Mutex.cpp
index 362a41533..843562aff 100644
--- a/Foundation/src/Mutex.cpp
+++ b/Foundation/src/Mutex.cpp
@@ -51,8 +51,6 @@ FastMutex::~FastMutex()
 }
 
 
-#ifdef POCO_HAVE_STD_ATOMICS
-
 SpinlockMutex::SpinlockMutex()
 {
 }
@@ -62,7 +60,5 @@ SpinlockMutex::~SpinlockMutex()
 {
 }
 
-#endif // POCO_HAVE_STD_ATOMICS
-
 
 } // namespace Poco