diff --git a/Include/Library.nsh b/Include/Library.nsh
index b9cc8f0e..6d41e0f6 100644
--- a/Include/Library.nsh
+++ b/Include/Library.nsh
@@ -89,7 +89,7 @@
   StrCpy $R3 $R3 -4 1
   IfFileExists $R3 +3
 
-    File /oname=$R2\NSIS.Library.RegTool.v2.exe "${NSISDIR}\Bin\RegTool.bin"
+    File /oname=$R2\NSIS.Library.RegTool.v2.$__INSTALLLLIB_SESSIONGUID.exe "${NSISDIR}\Bin\RegTool.bin"
     WriteRegStr HKLM "Software\Microsoft\Windows\CurrentVersion\RunOnce" \
       "NSIS.Library.RegTool.v2" '"$R2\NSIS.Library.RegTool.v2.$__INSTALLLLIB_SESSIONGUID.exe" /S'
 
diff --git a/Include/UpgradeDLL.nsh b/Include/UpgradeDLL.nsh
index 278f733e..ba10674c 100644
--- a/Include/UpgradeDLL.nsh
+++ b/Include/UpgradeDLL.nsh
@@ -71,7 +71,7 @@ Example:
   StrCpy $R3 $R3 -4 1
   IfFileExists $R3 +3
 
-    File /oname=$R2\NSIS.Library.RegTool.v2.exe "${NSISDIR}\Bin\RegTool.bin"
+    File /oname=$R2\NSIS.Library.RegTool.v2.$HWNDPARENT.exe "${NSISDIR}\Bin\RegTool.bin"
     WriteRegStr HKLM "Software\Microsoft\Windows\CurrentVersion\RunOnce" \
       "NSIS.Library.RegTool.v2" '"$R2\NSIS.Library.RegTool.v2.$HWNDPARENT.exe" /S'