diff --git a/CHANGELOG.md b/CHANGELOG.md
index 81dcb31..d14ee45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,19 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 Project website: https://github.com/mviereck/x11docker
 
+## [7.6.0](https://github.com/mviereck/x11docker/releases/tag/v7.6.0) - 2023-01-18
+### Changed
+ - Up to version 7.5.0 x11docker installed itself with prefix `/usr`,
+   now it uses `/usr/local`. This serves to follow the 
+   [Linux Foundation specifications of `/usr/local`.](https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch04s09.html).
+   To help with the transition, a new option `--remove-oldprefix`
+   was introduced. Recommended procedure:
+   - First run:      `x11docker --update`
+   - Afterwards run: `x11docker --remove-oldprefix`
+### Added
+ - `--remove-oldprefix`: Remove installation in old prefix `/usr`.
+   [(479)](https://github.com/mviereck/x11docker/issues/479)
+
 ## [7.5.0](https://github.com/mviereck/x11docker/releases/tag/v7.5.0) - 2023-01-16
 ### Added
  - `man` page for x11docker. (Run update from 7.4.2 twice to install it.)
@@ -21,7 +34,7 @@ Project website: https://github.com/mviereck/x11docker
    [(478)](https://github.com/mviereck/x11docker/issues/478)
  - Replace `getent` with custom `grep` command.
    [(477)](https://github.com/mviereck/x11docker/issues/477)
- - `--install|--update*`: Do not dpend on backend.
+ - `--install|--update*`: Do not depend on backend.
    [(470)](https://github.com/mviereck/x11docker/issues/470)
 ### Deprecated
  - `--backend=proot`: Deprecated because likely no one uses it,
diff --git a/README.md b/README.md
index d0f2195..6a5ddba 100644
--- a/README.md
+++ b/README.md
@@ -78,7 +78,8 @@ Files to work on can be shared between host and container.
 Since a while Docker distributes a version called "Docker Desktop" that runs Docker in a QEMU VM. x11docker is not designed to support this VM based version.
 Instead, use x11docker with the native ["Docker Engine Server version"](https://docs.docker.com/engine/install/#server) that uses your host kernel to run containers.
  - If you install Docker from your distribution's repository, you'll likely get this native version.
- - If you prefer podman over Docker, you'll don't need to care about this difference.
+ - The supported native Docker Engine package name is mostly `docker.io` or `docker-ce`, in opposite to the non-supported VM based `docker-desktop` package.
+ - If you prefer podman over Docker, you don't need to care about this difference.
 
 ### TL;DR
 For a quick start:
@@ -452,16 +453,18 @@ As root you can install, update and remove x11docker in system directories to be
  - `x11docker --update-master` : download and install latest master version from github.
  - `x11docker --remove` : remove all files installed by x11docker.
    - Note: This does not remove `~/.local/share/x11docker` where it stores persistent files of option `--home`.
+ - `x11docker --remove-oldprefix` : Before version 7.6.0 x11docker installed itself into `/usr/bin`.
+   Now it installs into `/usr/local/bin`. Use `--remove-oldprefix` to remove `/usr/bin` installations.
 
 To see the difference between current and coming updated version, you can use optional argument `diff` for `--update` and `--update-master`.
 Example: `x11docker --update-master=diff` will show you the code changes from your current installation to latest master/beta version without installing it.
 
 #### Installed files
 What the installation does (just for information):
- - Copies script `x11docker` to `/usr/bin`. 
- - Installs icon `x11docker.png` in `/usr/share/icons` using `xdg-icon-resource`. 
- - Copies documentation `README.md`, `CHANGELOG.md` and `LICENSE.txt` to `/usr/share/doc/x11docker`.
- - Stores `man` page for x11docker in `/usr/share/man/man1/x11docker.1.gz`.
+ - Copies script `x11docker` to `/usr/local/bin`. 
+ - Installs icon `x11docker.png` below `/usr/share/icons` using `xdg-icon-resource`. 
+ - Copies documentation `README.md`, `CHANGELOG.md` and `LICENSE.txt` to `/usr/local/share/doc/x11docker`.
+ - Stores `man` page for x11docker in `/usr/local/share/man/man1/x11docker.1.gz`.
  
 #### Shortest way for first installation:
  - For systems using `sudo`:
diff --git a/x11docker b/x11docker
index f263c06..f6f1e2c 100755
--- a/x11docker
+++ b/x11docker
@@ -11,7 +11,7 @@
 # Run 'x11docker --help' or scroll down to read usage information.
 # More documentation at:  https://github.com/mviereck/x11docker
 
-Version="7.5.0"
+Version="7.6.0"
 Packagedversion="no" # Set to "yes" if you want to package x11docker. This disables installation options.
 
 # --enforce-i: Enforce running in interactive mode to allow commands tty and weston-launch in special setups. (deprecated)
@@ -382,9 +382,9 @@ Installation options (need root permissions):
                        installed and new version without installing it.
      --remove          Remove x11docker from your system. Includes --cleanup.
                        Preserves ~/.local/share/x11docker from option --home.
---update, --update-master and --remove regard a possible custom installation
-path different from default /usr/bin directory.
-Additional options are disregarded."
+     --remove-oldprefix   Before version 7.6.0 x11docker installed itself
+                       into /usr/bin. Now it installs into /usr/local/bin.
+                       Use --remove-oldprefix to remove /usr/bin installations."
     ;;
   esac
 
@@ -1451,7 +1451,7 @@ writeaccess() {                 # check if useruid $1 has write access to folder
   [ "w" = "$(getfacl -pn "${2:-}" | grep "user:${1:-}:" | rev | cut -c2)" ] && return 0 || return 1
 }
 
-#### special jobs of x11docker (not running X or docker)
+#### special jobs of x11docker
 buildimage() {                  # --build: build image from x11docker repository Dockerfile
   # Build image $1 from x11docker repository
 
@@ -1642,30 +1642,25 @@ installer() {                   # --install, --update, --update-master, --remove
 
   ### FIXME: (--update)
   ### maybe not install additional files if x11docker is owned by user
-  local Key1= Key2= Oldversion= Newversion= Format=
-  local Binpath Binowner Bingroup Binpathdefault
+  local Key1= Key2= Oldversion= Newversion= Format= Prefix
+
+  Prefix="/usr/local"
 
-  Binpathdefault="/usr/bin"
-  # Detect existing installation location
   case "${1:-}" in
-    --install)
-      Binpath="$Binpathdefault"
-    ;;
-    --update|--update-master|--remove)
-      grep -q x11docker <<< "$0" && {
-        Binpath="$(dirname "$0")"
-        [ -d "$Binpath/.git" ] && Binpath="/usr/bin"
-        Binpath="$(myrealpath "$Binpath")"
-        Binowner="$(stat -c '%U' "$Binpath/x11docker")"
-        Bingroup="$(stat -c '%G' "$Binpath/x11docker")"
-      }
+    --remove-oldprefix)
+      Prefix="/usr"
+    ;;
+    *)
+      [ -x "/usr/bin/x11docker" ] && warning "Option ${1:-}: Detected x11docker installation in /usr/bin
+  Since version 7.6.0 x11docker defaults to ${Prefix}/bin instead.
+  If this was a custom installation without your package manager,
+  you can remove the old installation as root with:
+rm    /usr/bin/x11docker
+rm -R /usr/share/doc/x11docker
+rm    /usr/share/man/man1/x11docker.1.gz
+  or with x11docker option --remove-oldprefix"
     ;;
   esac
-  Binpath="${Binpath:-$Binpathdefault}"
-  Binowner="${Binowner:-root}"
-  Bingroup="${Bingroup:-root}"
-  [ "$Binpath" != "$Binpathdefault" ] && note "Option ${1:-}: Detected custom installation path:
-  $Binpath"
 
   [ "$Startuser" != "root" ] && {
     case "$Winsubsystem" in
@@ -1674,14 +1669,8 @@ installer() {                   # --install, --update, --update-master, --remove
         case "$Installerarg" in
           diff) ;;
           *)
-            case "$Binowner" in
-              root)
-                error "Must run as root to install, update or remove x11docker system wide."
-                return 1
-              ;;
-              *) warning "Option ${1:-}: Not running as root.
-  Installing or updating non-essential files in system wide folders might fail." ;;
-            esac
+            error "Must run as root to install, update or remove x11docker system wide."
+            return 1
           ;;
         esac
       ;;
@@ -1696,24 +1685,24 @@ installer() {                   # --install, --update, --update-master, --remove
   Try 'x11docker --update' instead."
         return 1
       }
-      command -v x11docker > /dev/null && {
+      [ -x "${Prefix}/bin/x11docker" ] && {
         warning "x11docker seems to be installed already
-  at $Binpath/x11docker.
+  at ${Prefix}/bin/x11docker.
   Will overwrite existing installation.
   Consider to use option '--update' or '--update-master' instead."
       }
     ;;
     --update|--update-master)
-      [ -x "$Binpath/x11docker" ] && {
-        Oldversion="$($Binpath/x11docker --version)"
+      [ -x "${Prefix}/bin/x11docker" ] && {
+        Oldversion="$(${Prefix}/bin/x11docker --version)"
         note "Current installed version: x11docker $Oldversion
-  at $Binpath/x11docker"
+  at ${Prefix}/bin/x11docker"
       } || {
         Oldversion=""
       }
 
-      [ -d /tmp/x11docker-install ] && rm -R /tmp/x11docker-install
-      mkdir -p /tmp/x11docker-install && cd /tmp/x11docker-install || {
+      [ -d     "/tmp/x11docker-install" ] && rm -R "/tmp/x11docker-install"
+      mkdir -p "/tmp/x11docker-install"   && cd    "/tmp/x11docker-install" || {
         error "Could not create or cd to /tmp/x11docker-install."
         return 1
       }
@@ -1742,7 +1731,7 @@ installer() {                   # --install, --update, --update-master, --remove
             error "Failed to download CHANGELOG.md from github."
             return 1
           }
-          Releaseversion="v$(cat CHANGELOG.md | grep "## \[" | grep -v 'Unreleased' | head -n1 | cut -d[ -f2 | cut -d] -f1)"
+          Releaseversion="v$(cat "CHANGELOG.md" | grep "## \[" | grep -v 'Unreleased' | head -n1 | cut -d[ -f2 | cut -d] -f1)"
           note "Downloading latest x11docker release $Releaseversion from github."
           download "https://codeload.github.com/mviereck/x11docker/$Format/$Releaseversion" "x11docker-update.$Format"  || {
             error "Failed to download x11docker from github."
@@ -1760,7 +1749,7 @@ installer() {                   # --install, --update, --update-master, --remove
         return 1
       }
       echo ""
-      cd /tmp/x11docker-install/$(ls -l | grep drwx | rev | cut -d' ' -f1 | rev) || {
+      cd "/tmp/x11docker-install/$(ls -l | grep drwx | rev | cut -d' ' -f1 | rev)" || {
         error "Could not cd to /tmp/x11docker-update/$(ls -l | grep drwx | rev | cut -d' ' -f1 | rev)"
         return 1
       }
@@ -1770,7 +1759,7 @@ installer() {                   # --install, --update, --update-master, --remove
   # New version number
   case "${1:-}" in
     --install|--update|--update-master)
-      Newversion="$(bash $(pwd)/x11docker --version)"
+      Newversion="$(bash "$(pwd)/x11docker" --version)"
     ;;
   esac
 
@@ -1807,7 +1796,7 @@ installer() {                   # --install, --update, --update-master, --remove
   case "${1:-}" in
     --update|--update-master)
       note "Excerpt of x11docker changelog:
-$(sed -n "/${Key1}/,/${Key2}/p" CHANGELOG.md | head -n-1)"
+$(sed -n "/${Key1}/,/${Key2}/p" "CHANGELOG.md" | head -n-1)"
     ;;
   esac
 
@@ -1816,8 +1805,8 @@ $(sed -n "/${Key1}/,/${Key2}/p" CHANGELOG.md | head -n-1)"
     case "${1:-}" in
       --update|--update-master)
         note "Difference of installed version to new version:
-  $ diff -u -s -Z $Binpath/x11docker $(pwd)/x11docker
-$(diff -u -s -Z $Binpath/x11docker $(pwd)/x11docker 2>&1 | sed "s/^+.*/${Colgreenbg}\0${Colnorm}/ ; s/^-.*/${Colredbg}\0${Colnorm}/ ; s/^@.*/${Coluline}\0${Colnorm}/")"
+  $ diff -u -s -Z '$(command -v x11docker)' '$(pwd)/x11docker'
+$(diff -u -s -Z "$(command -v x11docker)" "$(pwd)/x11docker" 2>&1 | sed "s/^+.*/${Colgreenbg}\0${Colnorm}/ ; s/^-.*/${Colredbg}\0${Colnorm}/ ; s/^@.*/${Coluline}\0${Colnorm}/")"
       ;;
     esac
   }
@@ -1825,50 +1814,49 @@ $(diff -u -s -Z $Binpath/x11docker $(pwd)/x11docker 2>&1 | sed "s/^+.*/${Colgree
   # Doing
   [ -z "$Installerarg" ] && case "${1:-}" in
     --install|--update|--update-master)
-      note "Installing x11docker in $Binpath"
-      cp x11docker "$Binpath/"                                                || {
-        error "Could not copy x11docker to $Binpath"
+      note "Installing x11docker to ${Prefix}/bin"
+      cp "x11docker" "${Prefix}/bin/"                                           || {
+        error "Could not copy x11docker to ${Prefix}/bin"
         return 1
       }
-      chmod 755 "$Binpath/x11docker"                                          || {
+      chmod 755 "${Prefix}/bin/x11docker"                                       || {
         error "Could not set executable bit on x11docker"
         return 1
       }
-      chown "$Binowner:$Bingroup" "$Binpath/x11docker"                        || warning "Could not set ownership '$Binowner:$Bingroup' to '$Binpath/x11docker'"
+      chown "root:root" "${Prefix}/bin/x11docker"                               || warning "Could not set ownership 'root:root' to '${Prefix}/bin/x11docker'"
 
       note "Installing icon for x11docker with xdg-icon-resource"
-      xdg-icon-resource install --context apps --novendor --mode system --size 64 "$(pwd)/x11docker.png" x11docker || warning "Could not install icon for x11docker.
+      xdg-icon-resource install --context apps --novendor --mode system --size 64 "$(pwd)/x11docker.png" "x11docker" || warning "Could not install icon for x11docker.
   Is 'xdg-icon-resource' (xdg-utils) installed on your system?"
-      xdg-icon-resource uninstall --size 72 x11docker ||:  # deprecated icon size, may still be present.
 
       note "Storing README.md, CHANGELOG.md and LICENSE.txt in
-  /usr/share/doc/x11docker"
-      mkdir -p /usr/share/doc/x11docker && {
-        cp README.md    /usr/share/doc/x11docker/
-        cp CHANGELOG.md /usr/share/doc/x11docker/
-        cp LICENSE.txt  /usr/share/doc/x11docker/
+  ${Prefix}/share/doc/x11docker"
+      mkdir -p "${Prefix}/share/doc/x11docker" && {
+        cp "README.md"    "${Prefix}/share/doc/x11docker/"
+        cp "CHANGELOG.md" "${Prefix}/share/doc/x11docker/"
+        cp "LICENSE.txt"  "${Prefix}/share/doc/x11docker/"
       } || note "Error while creating /usr/share/doc/x11docker"
 
-      note "Storing man page in /usr/share/man/man1/x11docker.1.gz"
+      note "Storing man page in ${Prefix}/share/man/man1/x11docker.1.gz"
       command -v gzip >/dev/null && {
-        gzip -c x11docker.man > /usr/share/man/man1/x11docker.1.gz
+        gzip -c "x11docker.man" > "${Prefix}/share/man/man1/x11docker.1.gz"
       } || note "Error storing man page."
 
       note "Installed x11docker version $Newversion"
     ;;
-    --remove)
+    --remove|--remove-oldprefix)
       note "Removing x11docker from your system."
-      cleanup
-      [ -x "$Binpath/x11docker" ]     && rm -v "$Binpath/x11docker"
-      [ -x "$Binpath/x11docker-gui" ] && rm -v "$Binpath/x11docker-gui"
-      [ -e "/usr/share/applications/x11docker.desktop" ] && rm -v /usr/share/applications/x11docker.desktop
-      [ -e "/usr/share/doc/x11docker" ]                  && rm -R -v /usr/share/doc/x11docker
-      [ -e "/usr/share/icons/x11docker.png" ]            && rm /usr/share/icons/x11docker.png
-      xdg-icon-resource uninstall --size 64 x11docker ||:
-      xdg-icon-resource uninstall --size 72 x11docker ||:  # deprecated icon size, may still be present.
+      [ "${1:-}" = "--remove" ] && [ -n "$Backendbin" ] && {
+        note "Running --cleanup"
+        cleanup
+      }
+      [ -x "${Prefix}/bin/x11docker"   ]               && rm -v    "${Prefix}/bin/x11docker"
+      [ -e "${Prefix}/share/doc/x11docker" ]           && rm -v -R "${Prefix}/share/doc/x11docker"
+      [ -e "${Prefix}/share/man/man1/x11docker.1.gz" ] && rm -v    "${Prefix}/share/man/man1/x11docker.1.gz"
+      [ "${1:-}" = "--remove" ] && xdg-icon-resource uninstall --size 64 "x11docker" ||:
       note "Will not remove files in your home folder.
-  There may be files left in \$HOME/.local/share/x11docker
-  The symbolic link \$HOME/x11docker may exist, too.
+  There might be files left in \$HOME/.local/share/x11docker
+  The symbolic link \$HOME/x11docker might exist, too.
   The cache folder \$HOME/.cache/x11docker should be removed already."
     ;;
   esac
@@ -1878,7 +1866,7 @@ $(diff -u -s -Z $Binpath/x11docker $(pwd)/x11docker 2>&1 | sed "s/^+.*/${Colgree
     --update|--update-master)
       note "Removing downloaded temporary files."
       cd ~
-      rm -R /tmp/x11docker-install
+      rm -R "/tmp/x11docker-install"
     ;;
   esac
   note "Ready."
@@ -5409,7 +5397,15 @@ check_backend() {               # options --backend, --rootless
 
   case "$Backend" in
     docker|podman|nerdctl|proot)
-      [ -z "$Backendbin" ] && error "Option --backend=$Backend: No binary found for $Backend."
+      case "$Installermode" in
+        "") 
+          [ -z "$Backendbin" ] && error "Option --backend=$Backend: No binary found for $Backend."
+        ;;
+        *)
+          [ -z "$Backendbin" ] && note "Option --backend=$Backend: No binary found for $Backend."
+          return 1
+        ;;
+      esac
     ;;
     host) Backendbin="" ;;
   esac
@@ -9203,7 +9199,7 @@ parse_options() {               # parse cli options
   Longoptions="$Longoptions,printenv::,printid::,printinfofile::,printpid1::"                                               # Output of vars on stdout
   Longoptions="$Longoptions,debug,printcheck,quiet,verbose::"                                                               # Verbose options
   Longoptions="$Longoptions,build,cleanup,help,launcher,licence,license,version"                                            # Special options without starting X or container
-  Longoptions="$Longoptions,install,remove,update::,update-master::"                                                        # Installation
+  Longoptions="$Longoptions,install,remove,remove-oldprefix,update::,update-master::"                                       # Installation
   #
   Longoptions="$Longoptions,experimental,keepcache,remountcgroup,xopt:,xorgconf:"                                           # Experimental
   Longoptions="$Longoptions,dbus-system,enforce-i,exe,homedir:,hostipc,hostnet,iglx,kwin-xwayland"                          # Deprecated
@@ -9400,11 +9396,11 @@ ${2:-}"                       ; shift ;;                             # Add custo
          --printpid1)         Showcontainerpid1pid="${2:-yes}" ; shift ;;       # Output of host PID of container PID 1
 
      #### Special options not starting X or docker
-         --build)             Buildimage="yes" ;;                    # Build an image from x11docker repository
-         --cleanup)           Cleanup="yes"  ;;                      # Remove orphaned containers and cache files
-         --install|--remove)  Installermode="${1:-}" ;;              # Installer
+         --build)             Buildimage="yes" ;;                               # Build an image from x11docker repository
+         --cleanup)           Cleanup="yes"  ;;                                 # Remove orphaned containers and cache files
+         --install|--remove|--remove-oldprefix) Installermode="${1:-}" ;;       # Installer
          --update|--update-master) Installermode="${1:-}" ; Installerarg="${2:-}" ; shift ;;   # Installer
-         --launcher)          Createlauncher="yes" ;;                # Create application launcher on desktop and exit
+         --launcher)          Createlauncher="yes" ;;                           # Create application launcher on desktop and exit
 
      #### Experimental options
          --experimental)      Experimental="yes" ;;                  # Allow some experimental code that might be changed at any time
@@ -11319,6 +11315,10 @@ unpriv() {                      # run a command as unprivileged user. Needed if
 unpriv_backend() {              # run container backend rootful or rootless
   local Command
   Command="$(oneline "${1:-}")"
+  [ -z "$Backendbin" ] && {
+    warning "Binary path for backend $Backend not set."
+    return 1
+  }
   case "$Backendrootless" in
     yes)   unpriv                  "$Command" ;;
     no|"") eval   "env DOCKER_HOST= $Command" ;;
@@ -11368,11 +11368,12 @@ main() {
     create_launcher                                                               # --launcher: Create application launcher icon on desktop
     finish
   }
+  check_backend                                                                   # --backend
   [ "$Installermode" ] && {                                                       # --install, --update, --update-master, --remove
     case "$Packagedversion" in
       yes)
         case "$Installermode" in
-          --install|--update|--update-master|--remove)
+          --install|--update|--update-master|--remove|--remove-oldprefix)
             error "Options --install|--update|--update-master|--remove
   are not supported in packaged versions of x11docker.
   Please use your package manager instead."
@@ -11380,11 +11381,10 @@ main() {
         esac
       ;;
     esac
-    check_optionset "$Installermode" "$(grep -v -E -- '--install|--update|--update-master|--remove' <<< "$Optionsetall")" ||:
+    check_optionset "$Installermode" "$(grep -v -E -- '--install|--update|--update-master|--remove|--remove-oldprefix' <<< "$Optionsetall")" ||:
     installer "$Installermode"
     finish
   }
-  check_backend                                                                   # --backend
   [ "$Cleanup" ] && {                                                             # --cleanup: Clean up cache and orphaned x11docker containers
     check_optionset "--cleanup" "$(grep -v -E -- '--cleanup|--backend' <<< "$Optionsetall")" ||:
     cleanup
diff --git a/x11docker.man b/x11docker.man
index 5ea1ca3..01e1e86 100644
--- a/x11docker.man
+++ b/x11docker.man
@@ -608,10 +608,11 @@ installed and new version without installing it.
 \fB\-\-remove\fR
 Remove x11docker from your system. Includes \fB\-\-cleanup\fR.
 Preserves \fI~/.local/share/x11docker\fR from option \fB\-\-home\fR.
-.PP
-\fB\-\-update\fR, \fB\-\-update\-master\fR and \fB\-\-remove\fR regard a possible custom installation
-path different from default \fI\,/usr/bin\/\fP directory.
-Additional options are disregarded.
+.TP
+\fB\-\-remove-oldprefix\fR
+Before version 7.6.0 x11docker installed itself
+into /usr/bin. Now it installs into /usr/local/bin.
+Use --remove-oldprefix to remove /usr/bin installations.
 
 
 .SH "DEPENDENCIES"