# NSIS CPack generator forcibly overwrites $INSTDIR to $DOCUMENTS for per-user JustMe installs
**URL:** https://discourse.cmake.org/t/nsis-cpack-generator-forcibly-overwrites-instdir-to-documents-for-per-user-justme-installs/15632
**Category:** Code
**Tags:** os:windows, cpack:nsis
**Created:** [April 27, 2026, 2:17pm UTC](https://discourse.cmake.org/t/nsis-cpack-generator-forcibly-overwrites-instdir-to-documents-for-per-user-justme-installs/15632 "2026-04-27T14:17:10Z")
**Posts on this page:** 1
**Page:** 1
### Author:  [@Nyoma\_Diamond](https://discourse.cmake.org/u/Nyoma_Diamond)
#### Post date: [April 27, 2026, 2:17pm UTC](https://discourse.cmake.org/t/nsis-cpack-generator-forcibly-overwrites-instdir-to-documents-for-per-user-justme-installs/15632/1 "2026-04-27T14:17:10Z")
Hiya
I’ve run into an issue with using the NSIS generator for CPack where it’s not possible to change the default install location for per-user `JustMe` installs. Specifically, if you wanted to change the default per-user install location `$INSTDIR` to something like `$LOCALAPPDATA\@CPACK_PACKAGE_INSTALL_DIRECTORY@` by setting `set(CPACK_NSIS_INSTALL_ROOT "$LOCALAPPDATA")` or something similar, CMake will automatically forcibly overwrite it and change `$INSTDIR` to `$DOCUMENTS\@CPACK_PACKAGE_INSTALL_DIRECTORY@`. This appears to be enforced by the default `NSIS.template.in` provided with CPack for some reason in the [default NSIS.template.in](https://gitlab.kitware.com/cmake/cmake/-/blob/master/Modules/Internal/CPack/NSIS.template.in?ref_type=heads#L957-973):
```auto
;--------------------------------
; determine admin versus local install
; Is install for "AllUsers" or "JustMe"?
; Default to "JustMe" - set to "AllUsers" if admin or on Win9x
; This function is used for the very first "custom page" of the installer.
; This custom page does not show up visibly, but it executes prior to the
; first visible page and sets up $INSTDIR properly...
; Choose different default installation folder based on SV_ALLUSERS...
; "Program Files" for AllUsers, "My Documents" for JustMe...
Function .onInit
;...
inst:
; Reads components status for registry
!insertmacro SectionList "InitSection"
; 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
; default
StrCpy $IS_DEFAULT_INSTALLDIR 0
StrCmp "$INSTDIR" "@CPACK_NSIS_INSTALL_ROOT@\@CPACK_PACKAGE_INSTALL_DIRECTORY@" 0 +2
StrCpy $IS_DEFAULT_INSTALLDIR 1
StrCpy $SV_ALLUSERS "JustMe"
; if default install dir then change the default
; if it is installed for JustMe
StrCmp "$IS_DEFAULT_INSTALLDIR" "1" 0 +2
StrCpy $INSTDIR "$DOCUMENTS\@CPACK_PACKAGE_INSTALL_DIRECTORY@"
;...
done:
StrCmp $SV_ALLUSERS "AllUsers" 0 +3
StrCmp "$IS_DEFAULT_INSTALLDIR" "1" 0 +2
StrCpy $INSTDIR "@CPACK_NSIS_INSTALL_ROOT@\@CPACK_PACKAGE_INSTALL_DIRECTORY@"
;...
FunctionEnd
```
By my interpretation, this actually reads like a design mistake, seemingly assuming that `@CPACK_NSIS_INSTALL_ROOT@` is always the default directory for an `AllUsers` installation (e.g., `C:/Program Files`), ignoring the case where `AllUsers` installations may be disabled (i.e., `JustMe` is enforced). In this case, the install directory is always forcibly changed to `$Documents`, no matter what `@CPACK_NSIS_INSTALL_ROOT@` is actually set to (including if it’s a local user directory), with no way to change the default install location.
As a result, it’s impossible to modify the install location to something sensible like `Users//AppData/Local/`, as CPack will hard enforce the default of `/Documents/`, which is frankly a poor location to install a program. It’s very strange that `CPACK_NSIS_INSTALL_ROOT` is even an option at all if CPack will always override and ignore it by default for per-user installs. Further, this behavior is entirely undocumented in the [CMake/CPack documentation](https://cmake.org/cmake/help/latest/cpack_gen/nsis.html), and is actually in effect contradictory to the existing explanation of `CPACK_NSIS_INSTALL_ROOT` if considering both the `AllUsers` and `JustMe` cases, as the `JustMe` case will always ignore `CPACK_NSIS_INSTALL_ROOT`:
> **CPACK\_NSIS\_INSTALL\_ROOT**
>
> The default installation directory presented to the end user by the NSIS installer is under this root dir. The full directory presented to the end user is: `${CPACK_NSIS_INSTALL_ROOT}/${CPACK_PACKAGE_INSTALL_DIRECTORY}`
I think the documentation for `CPACK_NSIS_INSTALL_ROOT` ought to specify it is only relevant for `AllUsers` install scopes and an additional variable should exist for handling the `JustMe` install scope (or at the very least, it should default to `$LOCALAPPDATA` instead of `$DOCUMENTS`). Additionally, by my reading it seems strange that the default behavior is to manually override the install directory to `$DOCUMENTS` and then manually change it _back_ to `CPACK_NSIS_INSTALL_ROOT` if the scope is `AllUsers` rather than just deciding the install path based on the scope directly.
Am I missing something? And do people have workarounds for this for user-only installers?