diff --git a/alc/alc.cpp b/alc/alc.cpp
index e84b26e5..30d363af 100644
--- a/alc/alc.cpp
+++ b/alc/alc.cpp
@@ -22,6 +22,11 @@
 
 #include "version.h"
 
+#ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#endif
+
 #include <exception>
 #include <algorithm>
 #include <array>
diff --git a/common/threads.cpp b/common/threads.cpp
index ff01de42..e3b715f0 100644
--- a/common/threads.cpp
+++ b/common/threads.cpp
@@ -20,12 +20,15 @@
 
 #include "config.h"
 
+#include "opthelpers.h"
 #include "threads.h"
 
 #include <system_error>
 
 
 #ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
 
 #include <limits>
 
@@ -73,15 +76,15 @@ semaphore::~semaphore()
 
 void semaphore::post()
 {
-    if(!ReleaseSemaphore(mSem, 1, nullptr))
+    if UNLIKELY(!ReleaseSemaphore(static_cast<HANDLE>(mSem), 1, nullptr))
         throw std::system_error(std::make_error_code(std::errc::value_too_large));
 }
 
 void semaphore::wait() noexcept
-{ WaitForSingleObject(mSem, INFINITE); }
+{ WaitForSingleObject(static_cast<HANDLE>(mSem), INFINITE); }
 
 bool semaphore::try_wait() noexcept
-{ return WaitForSingleObject(mSem, 0) == WAIT_OBJECT_0; }
+{ return WaitForSingleObject(static_cast<HANDLE>(mSem), 0) == WAIT_OBJECT_0; }
 
 } // namespace al
 
diff --git a/common/threads.h b/common/threads.h
index ff571a66..1cdb5d8f 100644
--- a/common/threads.h
+++ b/common/threads.h
@@ -11,12 +11,9 @@
 #define FORCE_ALIGN
 #endif
 
-#ifdef _WIN32
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-#elif defined(__APPLE__)
+#if defined(__APPLE__)
 #include <dispatch/dispatch.h>
-#else
+#elif !defined(_WIN32)
 #include <semaphore.h>
 #endif
 
@@ -26,7 +23,7 @@ namespace al {
 
 class semaphore {
 #ifdef _WIN32
-    using native_type = HANDLE;
+    using native_type = void*;
 #elif defined(__APPLE__)
     using native_type = dispatch_semaphore_t;
 #else