diff --git a/Common/CommonWindows.h b/Common/CommonWindows.h
index 4f43edb8ed..367223bb8b 100644
--- a/Common/CommonWindows.h
+++ b/Common/CommonWindows.h
@@ -1,6 +1,9 @@
 #pragma once
 
 #ifdef _WIN32
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
 #ifndef NOMINMAX
 #define NOMINMAX
 #endif
diff --git a/Common/Hash.cpp b/Common/Hash.cpp
index ae5cfb55b4..d03673db10 100644
--- a/Common/Hash.cpp
+++ b/Common/Hash.cpp
@@ -22,12 +22,6 @@
 #include <nmmintrin.h>
 #endif
 
-#ifdef _WIN32
-// Windows defines min/max which conflict with std::min/std::max.
-#undef min
-#undef max
-#endif
-
 static u64 (*ptrHashFunction)(const u8 *src, int len, u32 samples) = &GetMurmurHash3;
 
 // uint32_t
diff --git a/Common/StdMutex.h b/Common/StdMutex.h
index e5a9cfb1b7..40aeb02cfa 100644
--- a/Common/StdMutex.h
+++ b/Common/StdMutex.h
@@ -16,7 +16,6 @@
 #include <algorithm>
 
 #if defined(_WIN32) // WIN32
-#define WIN32_LEAN_AND_MEAN
 #include "CommonWindows.h"
 #else // POSIX
 #include <pthread.h>
diff --git a/Common/StdThread.h b/Common/StdThread.h
index 11d6755579..058e402e24 100644
--- a/Common/StdThread.h
+++ b/Common/StdThread.h
@@ -28,7 +28,6 @@
 #if defined(_WIN32)
 // WIN32
 
-#define WIN32_LEAN_AND_MEAN
 #include "CommonWindows.h"
 
 #if defined(_MSC_VER) && defined(_MT)
diff --git a/Core/HLE/sceDisplay.cpp b/Core/HLE/sceDisplay.cpp
index 123b7efa87..3780819525 100644
--- a/Core/HLE/sceDisplay.cpp
+++ b/Core/HLE/sceDisplay.cpp
@@ -46,12 +46,6 @@
 #include "../../GPU/GPUState.h"
 #include "../../GPU/GPUInterface.h"
 
-#ifdef _WIN32
-// Windows defines min/max which conflict with std::min/std::max.
-#undef min
-#undef max
-#endif
-
 struct FrameBufferState {
 	u32 topaddr;
 	PspDisplayPixelFormat pspFramebufFormat;
diff --git a/Core/HLE/sceKernelTime.cpp b/Core/HLE/sceKernelTime.cpp
index 6d32045762..e93866a24b 100644
--- a/Core/HLE/sceKernelTime.cpp
+++ b/Core/HLE/sceKernelTime.cpp
@@ -16,7 +16,6 @@
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
 #ifdef _WIN32
-#define WIN32_LEAN_AND_MEAN
 #include "Common/CommonWindows.h"
 #else
 #include <sys/time.h>
diff --git a/Core/HLE/sceRtc.cpp b/Core/HLE/sceRtc.cpp
index 6fa90b8d74..cf903c9bb2 100644
--- a/Core/HLE/sceRtc.cpp
+++ b/Core/HLE/sceRtc.cpp
@@ -17,6 +17,7 @@
 
 #ifdef _WIN32
 #include "Common/CommonWindows.h"
+#include <Winsock2.h>
 #else
 #include <sys/time.h>
 #endif
diff --git a/Core/MIPS/MIPSIntVFPU.cpp b/Core/MIPS/MIPSIntVFPU.cpp
index e106adae5c..46e6aea09b 100644
--- a/Core/MIPS/MIPSIntVFPU.cpp
+++ b/Core/MIPS/MIPSIntVFPU.cpp
@@ -1493,8 +1493,6 @@ namespace MIPSInt
 		PC += 4;
 	}
 
-#undef max
-
 	void Int_Vcst(u32 op)
 	{
 		int conNum = (op >> 16) & 0x1f;
diff --git a/Core/System.cpp b/Core/System.cpp
index f40c38e2d5..3258a7bc07 100644
--- a/Core/System.cpp
+++ b/Core/System.cpp
@@ -16,8 +16,6 @@
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
 #ifdef _WIN32
-#define NOMINMAX
-#define WIN32_LEAN_AND_MEAN
 #include "Common/CommonWindows.h"
 #endif
 
diff --git a/GPU/GLES/IndexGenerator.h b/GPU/GLES/IndexGenerator.h
index 74faa7823e..832bc01a75 100644
--- a/GPU/GLES/IndexGenerator.h
+++ b/GPU/GLES/IndexGenerator.h
@@ -21,7 +21,6 @@
 #include <algorithm>
 #include "CommonTypes.h"
 #include "../ge_constants.h"
-#undef max
 
 class IndexGenerator
 {
diff --git a/GPU/GLES/ShaderManager.cpp b/GPU/GLES/ShaderManager.cpp
index eb5385e5cf..3e3e5695bc 100644
--- a/GPU/GLES/ShaderManager.cpp
+++ b/GPU/GLES/ShaderManager.cpp
@@ -20,7 +20,6 @@
 #endif
 
 #ifdef SHADERLOG
-#define WIN32_LEAN_AND_MEAN
 #include "Common/CommonWindows.h"
 #endif
 
diff --git a/Windows/Debugger/CtrlDisAsmView.h b/Windows/Debugger/CtrlDisAsmView.h
index 01403d6055..b3b6f6059e 100644
--- a/Windows/Debugger/CtrlDisAsmView.h
+++ b/Windows/Debugger/CtrlDisAsmView.h
@@ -20,12 +20,10 @@
 
 #include "../../Core/Debugger/DebugInterface.h"
 
-#include <windows.h>
+#include "Common/CommonWindows.h"
 #include <vector>
 #include <algorithm>
 
-#undef min
-#undef max
 using std::min;
 using std::max;
 
diff --git a/Windows/DinputDevice.cpp b/Windows/DinputDevice.cpp
index 7f6fd0f378..1b24b1ef72 100644
--- a/Windows/DinputDevice.cpp
+++ b/Windows/DinputDevice.cpp
@@ -24,7 +24,7 @@
 #include "Core/Config.h"
 #include "input/input_state.h"
 #include "base/NativeApp.h"
-#include"input/keycodes.h"
+#include "input/keycodes.h"
 #include "Core/Reporting.h"
 #include "Xinput.h"
 #pragma comment(lib,"dinput8.lib")
diff --git a/Windows/OpenGLBase.h b/Windows/OpenGLBase.h
index a946a16039..7b35d6f0d2 100644
--- a/Windows/OpenGLBase.h
+++ b/Windows/OpenGLBase.h
@@ -2,8 +2,7 @@
 
 #pragma once
 
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
+#include "Common/CommonWindows.h"
 
 bool GL_Init(HWND window, std::string *error_message);