diff --git a/development/Win32/packaging/installer/LyXWinInstaller/MissingPrograms.nsh b/development/Win32/packaging/installer/LyXWinInstaller/MissingPrograms.nsh
index 71dbf18c6b..30b2e88972 100644
--- a/development/Win32/packaging/installer/LyXWinInstaller/MissingPrograms.nsh
+++ b/development/Win32/packaging/installer/LyXWinInstaller/MissingPrograms.nsh
@@ -151,7 +151,7 @@ Function MissingPrograms
    StrCpy $Acrobat "None"
   ${endif}
   ${if} $Acrobat != "None"
-   ReadRegStr $String HKCR "AcroExch.Document/shell/open/command" ""
+   ReadRegStr $String HKCR "AcroExch.Document\shell\open\command" ""
    StrCpy $Search "8" ; search for Acrobat or Adobe Reader 8 because then PDFViewWin8.exe is needed to view PDF-files
    !insertmacro StrPointer $String $Search $Pointer ; macro from LyXUtils
    ${if} $Pointer == "-1" ; if nothing was found