diff --git a/.github/scripts/Package-Windows.ps1 b/.github/scripts/Package-Windows.ps1
index 3e7dd464..55ae3688 100644
--- a/.github/scripts/Package-Windows.ps1
+++ b/.github/scripts/Package-Windows.ps1
@@ -119,6 +119,7 @@ function Package {
         Log-Information 'Creating InnoSetup installer...'
         Push-Location -Stack BuildTemp
         Ensure-Location -Path "${ProjectRoot}/release"
+        Remove-Item -Path Package -Recurse -Force -ErrorAction SilentlyContinue
         Copy-Item -Path ${Configuration} -Destination Package -Recurse
         Invoke-External iscc ${IsccFile} /O"${ProjectRoot}/release" /F"${OutputName}-Installer"
         Remove-Item -Path Package -Recurse
diff --git a/cmake/windows/resources/installer-Windows.iss.in b/cmake/windows/resources/installer-Windows.iss.in
index 656c3100..e94639d9 100644
--- a/cmake/windows/resources/installer-Windows.iss.in
+++ b/cmake/windows/resources/installer-Windows.iss.in
@@ -2,12 +2,13 @@
 #define MyAppVersion "@CMAKE_PROJECT_VERSION@"
 #define MyAppPublisher "@PLUGIN_AUTHOR@"
 #define MyAppURL "@PLUGIN_WEBSITE@"
+#define MyAppId "@UUID_APP@"
 
 [Setup]
 ; NOTE: The value of AppId uniquely identifies this application.
 ; Do not use the same AppId value in installers for other applications.
 ; (To generate a new GUID, click Tools | Generate GUID inside the IDE.)
-AppId={{@UUID_APP@}
+AppId={{{#MyAppId}}
 AppName={#MyAppName}
 AppVersion={#MyAppVersion}
 AppPublisher={#MyAppPublisher}
@@ -20,6 +21,7 @@ OutputBaseFilename={#MyAppName}-{#MyAppVersion}-Windows-Installer
 Compression=lzma
 SolidCompression=yes
 DirExistsWarning=no
+UsePreviousAppDir=no
 SetupIconFile=installer.ico
 UninstallDisplayIcon={app}\advanced-scene-switcher\data\res\images\logo.ico
 DisableDirPage=no
@@ -51,10 +53,34 @@ begin
   );
 end;
 
-// credit where it's due :
-// following function come from https://github.com/Xaymar/obs-studio_amf-encoder-plugin/blob/master/%23Resources/Installer.in.iss#L45
 function GetDirName(Value: string): string;
 begin
   Result := ExpandConstant('{commonappdata}\obs-studio\plugins');
 end;
 
+// Remove files placed by the legacy installer (obs-plugins/64bit and
+// data/obs-plugins layout) so the plugin is not loaded twice by OBS.
+// We read InstallLocation from our own previous uninstall entry, which is
+// the exact directory the old installer used regardless of OBS install path.
+procedure RemoveLegacyFiles();
+var
+  OldInstallPath: string;
+  UninstallKey: string;
+begin
+  UninstallKey := 'SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\' + '{' + '{#MyAppId}' + '}_is1';
+  if not RegQueryStringValue(HKLM, UninstallKey, 'InstallLocation', OldInstallPath) then
+    Exit;
+  DeleteFile(OldInstallPath + '\obs-plugins\64bit\advanced-scene-switcher.dll');
+  DeleteFile(OldInstallPath + '\obs-plugins\64bit\advanced-scene-switcher.pdb');
+  DeleteFile(OldInstallPath + '\obs-plugins\64bit\advanced-scene-switcher-lib.dll');
+  DeleteFile(OldInstallPath + '\obs-plugins\64bit\advanced-scene-switcher-lib.pdb');
+  DelTree(OldInstallPath + '\obs-plugins\64bit\advanced-scene-switcher-plugins', True, True, True);
+  DelTree(OldInstallPath + '\data\obs-plugins\advanced-scene-switcher', True, True, True);
+end;
+
+procedure CurStepChanged(CurStep: TSetupStep);
+begin
+  if CurStep = ssInstall then
+    RemoveLegacyFiles();
+end;
+