--- a/browser/installer/windows/nsis/installer.nsi
+++ b/browser/installer/windows/nsis/installer.nsi
@@ -833,26 +833,20 @@ Function LaunchApp
     Exec "$\"$INSTDIR\${FileMainEXE}$\""
   ${Else}
     GetFunctionAddress $0 LaunchAppFromElevatedProcess
     UAC::ExecCodeSegment $0
   ${EndIf}
 FunctionEnd
 
 Function LaunchAppFromElevatedProcess
-  ; Find the installation directory when launching using GetFunctionAddress
-  ; from an elevated installer since $INSTDIR will not be set in this installer
-  ${StrFilter} "${FileMainEXE}" "+" "" "" $R9
-  ReadRegStr $0 HKLM "Software\Clients\StartMenuInternet\$R9\DefaultIcon" ""
-  ${GetPathFromString} "$0" $0
-  ${GetParent} "$0" $1
   ; Set our current working directory to the application's install directory
   ; otherwise the 7-Zip temp directory will be in use and won't be deleted.
-  SetOutPath "$1"
-  Exec "$\"$0$\""
+  SetOutPath "$INSTDIR"
+  Exec "$\"$INSTDIR\${FileMainEXE}$\""
 FunctionEnd
 
 ################################################################################
 # Language
 
 !insertmacro MOZ_MUI_LANGUAGE 'baseLocale'
 !verbose push
 !verbose 3

--- a/browser/installer/windows/nsis/stub.nsi
+++ b/browser/installer/windows/nsis/stub.nsi
@@ -2060,25 +2060,19 @@ Function LaunchApp
     Exec "$\"$INSTDIR\${FileMainEXE}$\""
   ${Else}
     GetFunctionAddress $0 LaunchAppFromElevatedProcess
     UAC::ExecCodeSegment $0
   ${EndIf}
 FunctionEnd
 
 Function LaunchAppFromElevatedProcess
-  ; Find the installation directory when launching using GetFunctionAddress
-  ; from an elevated installer since $INSTDIR will not be set in this installer
-  ${StrFilter} "${FileMainEXE}" "+" "" "" $R9
-  ReadRegStr $0 HKLM "Software\Clients\StartMenuInternet\$R9\DefaultIcon" ""
-  ${GetPathFromString} "$0" $0
   ; Set the current working directory to the installation directory
-  ${GetParent} "$0" $1
-  SetOutPath "$1"
-  Exec "$\"$0$\""
+  SetOutPath "$INSTDIR"
+  Exec "$\"$INSTDIR\${FileMainEXE}$\""
 FunctionEnd
 
 Function CopyPostSigningData
   ${LineRead} "$EXEDIR\postSigningData" "1" $PostSigningData
   ${If} ${Errors}
     ClearErrors
     StrCpy $PostSigningData "0"
   ${Else}