diff --git a/modules/build/activation.nix b/modules/build/activation.nix
index 159bfe5..2817d83 100644
--- a/modules/build/activation.nix
+++ b/modules/build/activation.nix
@@ -15,6 +15,7 @@ let
   activationBinPaths = lib.makeBinPath [
     pkgs.bash
     pkgs.coreutils
+    pkgs.diffutils
     pkgs.findutils
     pkgs.gnused
     pkgs.ncurses          # For `tput`.
diff --git a/modules/environment/login/default.nix b/modules/environment/login/default.nix
index f1f04d5..38fcfa3 100644
--- a/modules/environment/login/default.nix
+++ b/modules/environment/login/default.nix
@@ -50,15 +50,33 @@ in
   config = {
 
     build.activation = {
-      installLoginScripts = ''
-        $DRY_RUN_CMD mkdir $VERBOSE_ARG --parents /bin /usr/lib
-        $DRY_RUN_CMD cp $VERBOSE_ARG ${login} /bin/login
-        $DRY_RUN_CMD cp $VERBOSE_ARG ${loginInner} /usr/lib/login-inner
+      installLogin = ''
+        if ! diff /bin/login ${login} > /dev/null; then
+          $DRY_RUN_CMD mkdir $VERBOSE_ARG --parents /bin
+          $DRY_RUN_CMD cp $VERBOSE_ARG ${login} /bin/.login.tmp
+          $DRY_RUN_CMD chmod $VERBOSE_ARG u+w /bin/.login.tmp
+          $DRY_RUN_CMD mv $VERBOSE_ARG /bin/.login.tmp /bin/login
+        fi
+      '';
+
+      installLoginInner = ''
+        if (test -e /usr/lib/.login-inner.new && ! diff /usr/lib/.login-inner.new ${loginInner} > /dev/null) || \
+            (! test -e /usr/lib/.login-inner.new && ! diff /usr/lib/login-inner ${loginInner} > /dev/null); then
+          $DRY_RUN_CMD mkdir $VERBOSE_ARG --parents /usr/lib
+          $DRY_RUN_CMD cp $VERBOSE_ARG ${loginInner} /usr/lib/.login-inner.tmp
+          $DRY_RUN_CMD chmod $VERBOSE_ARG u+w /usr/lib/.login-inner.tmp
+          $DRY_RUN_CMD mv $VERBOSE_ARG /usr/lib/.login-inner.tmp /usr/lib/.login-inner.new
+        fi
       '';
 
       installProotStatic = ''
-        $DRY_RUN_CMD mkdir $VERBOSE_ARG --parents /bin
-        $DRY_RUN_CMD cp $VERBOSE_ARG ${cfg.prootStatic}/bin/proot-static /bin/.proot-static.new
+        if (test -e /bin/.proot-static.new && ! diff /bin/.proot-static.new ${cfg.prootStatic}/bin/proot-static > /dev/null) || \
+            (! test -e /bin/.proot-static.new && ! diff /bin/proot-static ${cfg.prootStatic}/bin/proot-static > /dev/null); then
+          $DRY_RUN_CMD mkdir $VERBOSE_ARG --parents /bin
+          $DRY_RUN_CMD cp $VERBOSE_ARG ${cfg.prootStatic}/bin/proot-static /bin/.proot-static.tmp
+          $DRY_RUN_CMD chmod $VERBOSE_ARG u+w /bin/.proot-static.tmp
+          $DRY_RUN_CMD mv $VERBOSE_ARG /bin/.proot-static.tmp /bin/.proot-static.new
+        fi
       '';
     };
 
diff --git a/modules/environment/login/login.nix b/modules/environment/login/login.nix
index dc2d729..6219452 100644
--- a/modules/environment/login/login.nix
+++ b/modules/environment/login/login.nix
@@ -1,7 +1,7 @@
 # Licensed under GNU Lesser General Public License v3 or later, see COPYING.
 # Copyright (c) 2019 Alexander Sosedkin and other contributors, see AUTHORS.
 
-{ config, lib, writeScript }:
+{ config, writeScript }:
 
 let
   inherit (config.build) installationDir;
@@ -15,35 +15,23 @@ writeScript "login" ''
   export PROOT_TMP_DIR=${installationDir}/tmp
   export PROOT_L2S_DIR=${installationDir}/.l2s
 
-  ${
-    if config.build.initialBuild
-    then ''
-      ${installationDir}/bin/proot-static \
-        -b ${installationDir}/nix:/nix \
-        -b ${installationDir}/bin:/bin \
-        -b ${installationDir}/etc:/etc \
-        -b ${installationDir}/tmp:/tmp \
-        -b ${installationDir}/usr:/usr \
-        -b /:/android \
-        --link2symlink \
-        ${installationDir}/bin/sh ${installationDir}/usr/lib/login-inner "$@"
+  if test -e ${installationDir}/bin/.proot-static.new; then
+    echo "Install new proot-static..."
+    /system/bin/mv ${installationDir}/bin/.proot-static.new ${installationDir}/bin/proot-static
+  fi
 
-      exec ${installationDir}/bin/login "$@"
-    ''
-    else ''
-      if [[ -x ${installationDir}/bin/.proot-static.new ]] && ! $(/system/bin/pgrep proot-static); then
-        /system/bin/mv ${installationDir}/bin/.proot-static.new ${installationDir}/bin/proot-static
-      fi
+  if test -e ${installationDir}/usr/lib/.login-inner.new; then
+    echo "Install new login-inner..."
+    /system/bin/mv ${installationDir}/usr/lib/.login-inner.new ${installationDir}/usr/lib/login-inner
+  fi
 
-      exec ${installationDir}/bin/proot-static \
-        -b ${installationDir}/nix:/nix \
-        -b ${installationDir}/bin:/bin \
-        -b ${installationDir}/etc:/etc \
-        -b ${installationDir}/tmp:/tmp \
-        -b ${installationDir}/usr:/usr \
-        -b /:/android \
-        --link2symlink \
-        ${installationDir}/bin/sh ${installationDir}/usr/lib/login-inner "$@"
-    ''
-  }
+  exec ${installationDir}/bin/proot-static \
+    -b ${installationDir}/nix:/nix \
+    -b ${installationDir}/bin:/bin \
+    -b ${installationDir}/etc:/etc \
+    -b ${installationDir}/tmp:/tmp \
+    -b ${installationDir}/usr:/usr \
+    -b /:/android \
+    --link2symlink \
+    ${installationDir}/bin/sh ${installationDir}/usr/lib/login-inner "$@"
 ''