diff --git a/crc.cpp b/crc.cpp
index e1b51bb9..ccc3fe62 100644
--- a/crc.cpp
+++ b/crc.cpp
@@ -14,7 +14,7 @@ NAMESPACE_BEGIN(CryptoPP)
 #endif
 
 #if CRYPTOPP_BOOL_X86 || CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X64
-#if (CRYPTOPP_GCC_VERSION >= 40300 || __INTEL_COMPILER >= 1000 || __SUNPRO_CC >= 0x5110 || CRYPTOPP_LLVM_CLANG_VERSION >= 20300 || CRYPTOPP_APPLE_CLANG_VERSION >= 40000) && !defined(__SSE4_2__)
+#if (CRYPTOPP_GCC_VERSION >= 40300 || __INTEL_COMPILER >= 1000 || __SUNPRO_CC >= 0x5110 || CRYPTOPP_LLVM_CLANG_VERSION >= 20300 || CRYPTOPP_APPLE_CLANG_VERSION >= 40000) && !defined(__SSE4_2__) && !defined(_MSC_VER)
 GCC_INLINE unsigned int GCC_INLINE_ATTRIB
 MM_CRC32_U8(unsigned int crc, unsigned char val)
 {
diff --git a/dll.cpp b/dll.cpp
index bc406de2..372ed712 100644
--- a/dll.cpp
+++ b/dll.cpp
@@ -121,7 +121,7 @@ static void SetNewAndDeleteFunctionPointers()
 			return;
 	}
 
-	OutputDebugString("Crypto++ DLL was not able to obtain new and delete function pointers.\n");
+	OutputDebugStringA("Crypto++ DLL was not able to obtain new and delete function pointers.\n");
 	throw 0;
 }
 
diff --git a/fipstest.cpp b/fipstest.cpp
index a7419821..132c6510 100644
--- a/fipstest.cpp
+++ b/fipstest.cpp
@@ -328,21 +328,21 @@ bool IntegrityCheckModule(const char *moduleFilename, const byte *expectedModule
 	{
 		std::ostringstream oss;
 		oss << "Crypto++ DLL loaded at base address 0x" << std::hex << h << ".\n";
-		OutputDebugString(oss.str().c_str());
+		OutputDebugStringA(oss.str().c_str());
 	}
 	else
 	{
 		std::ostringstream oss;
 		oss << "Crypto++ DLL integrity check may fail. Expected module base address is 0x";
 		oss << std::hex << g_BaseAddressOfMAC << ", but module loaded at 0x" << h << ".\n";
-		OutputDebugString(oss.str().c_str());
+		OutputDebugStringA(oss.str().c_str());
 	}
 #endif
 
 	if (!moduleStream)
 	{
 #ifdef CRYPTOPP_WIN32_AVAILABLE
-		OutputDebugString("Crypto++ DLL integrity check failed. Cannot open file for reading.");
+		OutputDebugStringA("Crypto++ DLL integrity check failed. Cannot open file for reading.");
 #endif
 		return false;
 	}
@@ -400,7 +400,7 @@ bool IntegrityCheckModule(const char *moduleFilename, const byte *expectedModule
 					}
 				}
 
-#if defined(_MSC_VER) && _MSC_VER >= 1400
+#if defined(_MSC_VER) && _MSC_VER >= 1400 && !defined(_M_ARM)
 				// first byte of _CRT_DEBUGGER_HOOK gets modified in memory by the debugger invisibly, so read it from file
 				if (IsDebuggerPresent())
 				{
@@ -436,7 +436,7 @@ bool IntegrityCheckModule(const char *moduleFilename, const byte *expectedModule
 	// hash from disk instead
 	if (!VerifyBufsEqual(expectedModuleMac, actualMac, macSize))
 	{
-		OutputDebugString("Crypto++ DLL in-memory integrity check failed. This may be caused by debug breakpoints or DLL relocation.\n");
+		OutputDebugStringA("Crypto++ DLL in-memory integrity check failed. This may be caused by debug breakpoints or DLL relocation.\n");
 		moduleStream.clear();
 		moduleStream.seekg(0);
 		verifier.Initialize(MakeParameters(Name::OutputBuffer(), ByteArrayParameter(actualMac, (unsigned int)actualMac.size())));
@@ -455,7 +455,7 @@ bool IntegrityCheckModule(const char *moduleFilename, const byte *expectedModule
 #ifdef CRYPTOPP_WIN32_AVAILABLE
 	std::string hexMac;
 	HexEncoder(new StringSink(hexMac)).PutMessageEnd(actualMac, actualMac.size());
-	OutputDebugString((("Crypto++ DLL integrity check failed. Actual MAC is: " + hexMac) + ".\n").c_str());
+	OutputDebugStringA((("Crypto++ DLL integrity check failed. Actual MAC is: " + hexMac) + ".\n").c_str());
 #endif
 	return false;
 }
diff --git a/integer.cpp b/integer.cpp
index 13a58a4e..cb38ca29 100644
--- a/integer.cpp
+++ b/integer.cpp
@@ -41,8 +41,10 @@
 
 #if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
 # pragma GCC diagnostic ignored "-Wunused"
+#if !defined(__clang__)
 # pragma GCC diagnostic ignored "-Wunused-but-set-variable"
 #endif
+#endif
 
 // Issue 340
 #if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
diff --git a/iterhash.cpp b/iterhash.cpp
index eedd5172..bf287164 100644
--- a/iterhash.cpp
+++ b/iterhash.cpp
@@ -152,7 +152,7 @@ template <class T, class BASE> void IteratedHashBase<T, BASE>::TruncatedFinal(by
 	this->Restart();		// reinit for next use
 }
 
-#ifdef __GNUC__
+#if defined(__GNUC__) || defined(__clang__)
 	template class IteratedHashBase<word64, HashTransformation>;
 	template class IteratedHashBase<word64, MessageAuthenticationCode>;
 
diff --git a/iterhash.h b/iterhash.h
index 5ab38825..d51e155b 100644
--- a/iterhash.h
+++ b/iterhash.h
@@ -179,7 +179,7 @@ protected:
 	FixedSizeAlignedSecBlock<T_HashWordType, T_BlockSize/sizeof(T_HashWordType), T_StateAligned> m_state;
 };
 
-#ifndef __GNUC__
+#if !defined(__GNUC__) && !defined(__clang__)
 	CRYPTOPP_DLL_TEMPLATE_CLASS IteratedHashBase<word64, HashTransformation>;
 	CRYPTOPP_STATIC_TEMPLATE_CLASS IteratedHashBase<word64, MessageAuthenticationCode>;
 
diff --git a/network.cpp b/network.cpp
index 9195e22b..c7873d0e 100644
--- a/network.cpp
+++ b/network.cpp
@@ -287,7 +287,7 @@ size_t NetworkSource::DoPump(lword &byteCount, bool blockingOutput, unsigned lon
 
 				unsigned int recvResult = receiver.GetReceiveResult();
 #if CRYPTOPP_TRACE_NETWORK
-				OutputDebugString((IntToString((unsigned int)this) + ": Received " + IntToString(recvResult) + " bytes\n").c_str());
+				OutputDebugStringA((IntToString((unsigned int)this) + ": Received " + IntToString(recvResult) + " bytes\n").c_str());
 #endif
 				m_dataEnd += recvResult;
 				m_waitingForResult = false;
@@ -315,13 +315,13 @@ ReceiveNoWait:
 					// call Receive repeatedly as long as data is immediately available,
 					// because some receivers tend to return data in small pieces
 #if CRYPTOPP_TRACE_NETWORK
-					OutputDebugString((IntToString((unsigned int)this) + ": Receiving " + IntToString(m_buf.size()-m_dataEnd) + " bytes\n").c_str());
+					OutputDebugStringA((IntToString((unsigned int)this) + ": Receiving " + IntToString(m_buf.size()-m_dataEnd) + " bytes\n").c_str());
 #endif
 					while (receiver.Receive(m_buf+m_dataEnd, m_buf.size()-m_dataEnd))
 					{
 						unsigned int recvResult = receiver.GetReceiveResult();
 #if CRYPTOPP_TRACE_NETWORK
-						OutputDebugString((IntToString((unsigned int)this) + ": Received " + IntToString(recvResult) + " bytes\n").c_str());
+						OutputDebugStringA((IntToString((unsigned int)this) + ": Received " + IntToString(recvResult) + " bytes\n").c_str());
 #endif
 						m_dataEnd += recvResult;
 						if (receiver.EofReceived() || m_dataEnd > m_buf.size() /2)
@@ -391,7 +391,7 @@ float NetworkSink::ComputeCurrentSpeed()
 		m_maxObservedSpeed = STDMAX(m_currentSpeed, m_maxObservedSpeed * 0.98f);
 		m_byteCountSinceLastTimerReset = 0;
 		m_speedTimer.StartTimer();
-//		OutputDebugString(("max speed: " + IntToString((int)m_maxObservedSpeed) + " current speed: " + IntToString((int)m_currentSpeed) + "\n").c_str());
+//		OutputDebugStringA(("max speed: " + IntToString((int)m_maxObservedSpeed) + " current speed: " + IntToString((int)m_currentSpeed) + "\n").c_str());
 	}
 	return m_currentSpeed;
 }
@@ -497,7 +497,7 @@ lword NetworkSink::DoFlush(unsigned long maxTime, size_t targetSize)
 
 			unsigned int sendResult = sender.GetSendResult();
 #if CRYPTOPP_TRACE_NETWORK
-			OutputDebugString((IntToString((unsigned int)this) + ": Sent " + IntToString(sendResult) + " bytes\n").c_str());
+			OutputDebugStringA((IntToString((unsigned int)this) + ": Sent " + IntToString(sendResult) + " bytes\n").c_str());
 #endif
 			m_buffer.Skip(sendResult);
 			totalFlushSize += sendResult;
@@ -515,7 +515,7 @@ lword NetworkSink::DoFlush(unsigned long maxTime, size_t targetSize)
 		const byte *block = m_buffer.Spy(contiguousSize);
 
 #if CRYPTOPP_TRACE_NETWORK
-		OutputDebugString((IntToString((unsigned int)this) + ": Sending " + IntToString(contiguousSize) + " bytes\n").c_str());
+		OutputDebugStringA((IntToString((unsigned int)this) + ": Sending " + IntToString(contiguousSize) + " bytes\n").c_str());
 #endif
 		sender.Send(block, contiguousSize);
 		m_needSendResult = true;
diff --git a/wait.cpp b/wait.cpp
index c6a74d94..3356a0d0 100644
--- a/wait.cpp
+++ b/wait.cpp
@@ -373,7 +373,7 @@ bool WaitObjectContainer::Wait(unsigned long milliseconds)
 		if (milliseconds > 0)
 		{
 			unsigned long timeAfterWait = t.ElapsedTime();
-			OutputDebugString(("Handles " + IntToString(m_handles.size()) + ", Woke up by " + IntToString(result-WAIT_OBJECT_0) + ", Busied for " + IntToString(timeBeforeWait-lastTime) + " us, Waited for " + IntToString(timeAfterWait-timeBeforeWait) + " us, max " + IntToString(milliseconds) + "ms\n").c_str());
+			OutputDebugStringA(("Handles " + IntToString(m_handles.size()) + ", Woke up by " + IntToString(result-WAIT_OBJECT_0) + ", Busied for " + IntToString(timeBeforeWait-lastTime) + " us, Waited for " + IntToString(timeAfterWait-timeBeforeWait) + " us, max " + IntToString(milliseconds) + "ms\n").c_str());
 			lastTime = timeAfterWait;
 		}
 #endif