diff --git a/Installation/Windows/Templates/NSIS.template.in b/Installation/Windows/Templates/NSIS.template.in
index 9559e7ab98..8b953c8bcf 100755
--- a/Installation/Windows/Templates/NSIS.template.in
+++ b/Installation/Windows/Templates/NSIS.template.in
@@ -1262,9 +1262,10 @@ Section "Uninstall"
   SimpleSC::GetServiceBinaryPath '${TRI_SVC_NAME}'
   Pop $0 ; returns an errorcode (<>0) otherwise success (0)
   Pop $1 ; returns the binary path of the service
-  ; $1 should contain '"$INSTDIR/${SBIN_DIR}/arangod.exe" --start-service' - if $INSTDIR is equal
+  ; $1 should contain '"$INSTDIR\${SBIN_DIR}\arangod.exe" --start-service' - if $INSTDIR is equal
   ; to our $INSTDIR uninstall the service - else its another installation and we jump to Done instead.
-  StrCmp $1 '"$INSTDIR/${SBIN_DIR}/arangod.exe" --start-service' '' Done
+  ; MessageBox MB_OK ' current service: $1 ---- "$INSTDIR\${SBIN_DIR}\arangod.exe"'
+  StrCmp $1 '"$INSTDIR\${SBIN_DIR}\arangod.exe" --start-service' '' Done
   DetailPrint 'Shutting down Service'
   SimpleSC::StopService  '${TRI_SVC_NAME}' 0 30
   Call un.WaitForServiceDown
@@ -1379,43 +1380,44 @@ var CMDINSTDIR
 Function .onInit
   ${GetParameters} $R0
   ClearErrors
-  ${GetOptions} $R0 "/PASSWORD="    $PASSWORD
+  ${GetOptions} $R0 "/PASSWORD="       $PASSWORD
   IfErrors 0 +2
-  StrCpy $PASSWORD ""
-        
+  ReadEnvStr $PASSWORD PASSWORD
+  
+  # we only want to manipulate INSTDIR here if /INSTDIR is realy set!
   ${GetParameters} $R0        
   ClearErrors
-  ${GetOptions} $R0 "/INSTDIR="     $CMDINSTDIR
+  ${GetOptions} $R0 "/INSTDIR="        $CMDINSTDIR
   IfErrors +2 0
   StrCpy $INSTDIR "$CMDINSTDIR"
 
+  ${GetParameters} $R0
+  ClearErrors
+  ${GetOptions} $R0 "/STORAGE_ENGINE=" $STORAGE_ENGINE
+  IfErrors 0 +2
+  StrCpy $STORAGE_ENGINE "auto"
+
   ${GetParameters} $R0        
-  ${GetOptions} $R0 "/DESKTOPICON=" $INSTALL_DESKTOP
+  ${GetOptions} $R0 "/DESKTOPICON="    $INSTALL_DESKTOP
   IfErrors 0 +2
   StrCpy $INSTALL_DESKTOP "1"
         
   ${GetParameters} $R0
   ClearErrors
-  ${GetOptions} $R0 "/NOPATH="       $DO_NOT_ADD_TO_PATH
+  ${GetOptions} $R0 "/NOPATH="         $DO_NOT_ADD_TO_PATH
   IfErrors 0 +2
   StrCpy $DO_NOT_ADD_TO_PATH "0"
 
   ${GetParameters} $R0
   ClearErrors
-  ${GetOptions} $R0 "/ALLPATH="      $ADD_TO_PATH_ALL_USERS
+  ${GetOptions} $R0 "/ALLPATH="        $ADD_TO_PATH_ALL_USERS
   IfErrors 0 +2
   StrCpy $ADD_TO_PATH_ALL_USERS "0"
-        
-  ${GetParameters} $R0
-  ClearErrors
-  ${GetOptions} $R0 "/CURPATH="      $ADD_TO_PATH_CURRENT_USER
-  IfErrors 0 +3
-  StrCpy $ADD_TO_PATH_CURRENT_USER "0"
 
   ${GetParameters} $R0
   ClearErrors
-  ${GetOptions} $R0 "/STORAGE_ENGINE="      $STORAGE_ENGINE
-  IfErrors 0 +3
+  ${GetOptions} $R0 "/CURPATH="        $ADD_TO_PATH_CURRENT_USER
+  IfErrors 0 +2
   StrCpy $ADD_TO_PATH_CURRENT_USER "0"
 
   IfSilent 0 dontValidatePathOption
@@ -1467,7 +1469,6 @@ inst:
   ; Reads components status for registry
   !insertmacro SectionList "InitSection"
 
-  StrCpy $STORAGE_ENGINE "auto"
   ; check to see if /D has been used to change
   ; the install directory by comparing it to the
   ; install directory that is expected to be the