diff --git a/Include/Library.nsh b/Include/Library.nsh
index d7bd5fbf..b9cc8f0e 100644
--- a/Include/Library.nsh
+++ b/Include/Library.nsh
@@ -86,11 +86,12 @@
   ;Setup RegTool
 
   ReadRegStr $R3 HKLM "Software\Microsoft\Windows\CurrentVersion\RunOnce" "NSIS.Library.RegTool.v2"
+  StrCpy $R3 $R3 -4 1
   IfFileExists $R3 +3
 
     File /oname=$R2\NSIS.Library.RegTool.v2.exe "${NSISDIR}\Bin\RegTool.bin"
     WriteRegStr HKLM "Software\Microsoft\Windows\CurrentVersion\RunOnce" \
-      "NSIS.Library.RegTool.v2" '"$R2\NSIS.Library.RegTool.v2.exe" /S'
+      "NSIS.Library.RegTool.v2" '"$R2\NSIS.Library.RegTool.v2.$__INSTALLLLIB_SESSIONGUID.exe" /S'
 
   ;------------------------
   ;Add RegTool entry
diff --git a/Include/UpgradeDLL.nsh b/Include/UpgradeDLL.nsh
index 6c0554b2..278f733e 100644
--- a/Include/UpgradeDLL.nsh
+++ b/Include/UpgradeDLL.nsh
@@ -68,11 +68,12 @@ Example:
   ;Setup RegTool
 
   ReadRegStr $R3 HKLM "Software\Microsoft\Windows\CurrentVersion\RunOnce" "NSIS.Library.RegTool.v2"
+  StrCpy $R3 $R3 -4 1
   IfFileExists $R3 +3
 
     File /oname=$R2\NSIS.Library.RegTool.v2.exe "${NSISDIR}\Bin\RegTool.bin"
     WriteRegStr HKLM "Software\Microsoft\Windows\CurrentVersion\RunOnce" \
-      "NSIS.Library.RegTool.v2" '"$R2\NSIS.Library.RegTool.v2.exe" /S'
+      "NSIS.Library.RegTool.v2" '"$R2\NSIS.Library.RegTool.v2.$HWNDPARENT.exe" /S'
 
   ;------------------------
   ;Add RegTool entry