diff --git a/Foundation/include/Poco/FIFOBuffer.h b/Foundation/include/Poco/FIFOBuffer.h
index 7f5022306..9c73b7e7a 100644
--- a/Foundation/include/Poco/FIFOBuffer.h
+++ b/Foundation/include/Poco/FIFOBuffer.h
@@ -284,7 +284,7 @@ public:
 	std::size_t available() const
 		/// Returns the size of the available portion of the buffer.
 	{
-		return _buffer.size() - _used;
+		return size() - _used;
 	}
 
 	void drain(std::size_t length = 0)
@@ -361,6 +361,9 @@ public:
 		Mutex::ScopedLock lock(_mutex);
 		if (_begin != 0)
 		{
+			// Move the data to the start of the buffer so begin() and next()
+			// always return consistent pointers with each other and allow writing
+			// to the end of the buffer.
 			std::memmove(_buffer.begin(), _buffer.begin() + _begin, _used * sizeof(T));
 			_begin = 0;
 		}
@@ -371,16 +374,7 @@ public:
 		/// Returns the pointer to the next available position in the buffer.
 	{
 		Mutex::ScopedLock lock(_mutex);
-		if (available() == 0)
-			throw InvalidAccessException("Buffer is full.");
-
-		if (_begin != 0)
-		{
-			std::memmove(_buffer.begin(), _buffer.begin() + _begin, _used * sizeof(T));
-			_begin = 0;
-		}
-
-		return _buffer.begin() + _used;
+		return begin() + _used;
 	}
 
 	T& operator [] (std::size_t index)