diff --git a/aegisub/src/agi_pre.h b/aegisub/src/agi_pre.h
index ef70361d2..e4e185aa3 100644
--- a/aegisub/src/agi_pre.h
+++ b/aegisub/src/agi_pre.h
@@ -89,16 +89,15 @@
 #include <wchar.h>
 
 #ifdef _WIN32
+// "Lean and mean" causes windows.h to include less stuff, mostly rarely-used things.
+// We can't build without being "lean and mean", some of the things included by it has
+// macros that clash with variable names around Aegisub causing strange build errors.
 #define WIN32_LEAN_AND_MEAN
+// Windows.h must always be the first one, it defines a load of important things
 #include <windows.h>
+#include <objbase.h>
 #include <mmsystem.h>
-#include <dsound.h>
-#include <process.h>
-//#include <objbase.h>
-#include <shlobj.h>
-#include <tchar.h>
-#include <vfw.h>
-//#include <windef.h>
+//#include <process.h> // Currently only used in audio_player_dsound2.cpp
 
 #else
 
diff --git a/aegisub/src/audio_player_dsound2.cpp b/aegisub/src/audio_player_dsound2.cpp
index 17a68c7a0..94911f6e8 100644
--- a/aegisub/src/audio_player_dsound2.cpp
+++ b/aegisub/src/audio_player_dsound2.cpp
@@ -42,10 +42,10 @@
 #ifdef WITH_DIRECTSOUND
 
 #ifndef AGI_PRE
-#include <dsound.h>
 #include <mmsystem.h>
-#include <process.h>
 #endif
+#include <process.h>
+#include <dsound.h>
 
 #include "audio_player_dsound2.h"
 #include "frame_main.h"
diff --git a/aegisub/src/font_file_lister_freetype.cpp b/aegisub/src/font_file_lister_freetype.cpp
index 0932eee5f..b9f7885bb 100644
--- a/aegisub/src/font_file_lister_freetype.cpp
+++ b/aegisub/src/font_file_lister_freetype.cpp
@@ -43,13 +43,10 @@
 #ifdef WITH_FREETYPE2
 
 #ifndef AGI_PRE
-#ifdef __WINDOWS__
-#include <shlobj.h>
-#endif
-
 #include <wx/dir.h>
 #endif
 
+#include <shlobj.h>
 #include <ft2build.h>
 #include FT_FREETYPE_H
 #include FT_GLYPH_H
diff --git a/aegisub/src/vfw_wrap.cpp b/aegisub/src/vfw_wrap.cpp
index a3c5737d7..d17a6e2ad 100644
--- a/aegisub/src/vfw_wrap.cpp
+++ b/aegisub/src/vfw_wrap.cpp
@@ -42,11 +42,7 @@
 // Headers
 #include "config.h"
 
-#ifndef AGI_PRE
-#ifdef __WINDOWS__
 #include <vfw.h>
-#endif
-#endif
 
 #include "vfw_wrap.h"