diff --git a/docs/directory_structure.md b/docs/directory_structure.md
--- a/docs/directory_structure.md
+++ b/docs/directory_structure.md
@@ -19,14 +19,14 @@ 2. Your personal directory
     - Windows:
         - `C:\My Documents\OpenTTD` (95, 98, ME)
         - `C:\Documents and Settings\<username>\My Documents\OpenTTD` (2000, XP)
-        - `C:\Users\<username>\Documents\OpenTTD` (Vista, 7, 8.1, 10, 11)
+        - `C:\Users\<username>\Documents\OpenTTD` (7, 8.1, 10, 11)
     - macOS: `~/Documents/OpenTTD`
     - Linux: `$XDG_DATA_HOME/openttd` which is usually `~/.local/share/openttd`
        when built with XDG base directory support, otherwise `~/.openttd`
 3. The shared directory
     - Windows:
         - `C:\Documents and Settings\All Users\Shared Documents\OpenTTD` (2000, XP)
-        - `C:\Users\Public\Documents\OpenTTD` (Vista, 7, 8.1, 10, 11)
+        - `C:\Users\Public\Documents\OpenTTD` (7, 8.1, 10, 11)
     - macOS: `/Library/Application Support/OpenTTD`
     - Linux: not available
 4. The binary directory (where the OpenTTD executable is)
diff --git a/os/windows/openttd.manifest b/os/windows/openttd.manifest
--- a/os/windows/openttd.manifest
+++ b/os/windows/openttd.manifest
@@ -15,8 +15,6 @@
   </application>
   <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
     <application>
-      <!--This Id value indicates the application supports Windows Vista functionality -->
-      <supportedOS Id="{e2011457-1546-43c5-a5fe-008deee3d3f0}"/>
       <!--This Id value indicates the application supports Windows 7 functionality-->
       <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/>
       <!--This Id value indicates the application supports Windows 8 functionality-->
diff --git a/src/sound/win32_s.cpp b/src/sound/win32_s.cpp
--- a/src/sound/win32_s.cpp
+++ b/src/sound/win32_s.cpp
@@ -70,7 +70,7 @@ const char *SoundDriver_Win32::Start(con
 	wfex.nAvgBytesPerSec = wfex.nSamplesPerSec * wfex.nBlockAlign;
 
 	/* Limit buffer size to prevent overflows. */
-	_bufsize = GetDriverParamInt(parm, "bufsize", IsWindowsVistaOrGreater() ? 8192 : 4096);
+	_bufsize = GetDriverParamInt(parm, "bufsize", 8192);
 	_bufsize = std::min<int>(_bufsize, UINT16_MAX);
 
 	try {
diff --git a/src/video/win32_v.cpp b/src/video/win32_v.cpp
--- a/src/video/win32_v.cpp
+++ b/src/video/win32_v.cpp
@@ -1258,7 +1258,7 @@ static const char *SelectPixelFormat(HDC
 		0, 0, 0, 0                     // Ignored/reserved.
 	};
 
-	if (IsWindowsVistaOrGreater()) pfd.dwFlags |= PFD_SUPPORT_COMPOSITION; // Make OpenTTD compatible with Aero.
+	pfd.dwFlags |= PFD_SUPPORT_COMPOSITION; // Make OpenTTD compatible with Aero.
 
 	/* Choose a suitable pixel format. */
 	int format = ChoosePixelFormat(dc, &pfd);