diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index a41309e93..fd0f54184 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -278,73 +278,9 @@ EOF
     fi
 
     if type nix-env 2> /dev/null >&2; then
-        failure <<EOF
-Nix already appears to be installed, and this tool assumes it is
-_not_ yet installed.
-
-$(uninstall_directions)
-EOF
-    fi
-
-    if [ "${NIX_REMOTE:-}" != "" ]; then
-        failure <<EOF
-For some reason, \$NIX_REMOTE is set. It really should not be set
-before this installer runs, and it hints that Nix is currently
-installed. Please delete the old Nix installation and start again.
-
-Note: You might need to close your shell window and open a new shell
-to clear the variable.
-EOF
-    fi
-
-    if echo "${SSL_CERT_FILE:-}" | grep -qE "(nix/var/nix|nix-profile)"; then
-        failure <<EOF
-It looks like \$SSL_CERT_FILE is set to a path that used to be part of
-the old Nix installation. Please unset that variable and try again:
-
-  $ unset SSL_CERT_FILE
-
-EOF
-    fi
-
-    for file in ~/.bash_profile ~/.bash_login ~/.profile ~/.zshenv ~/.zprofile ~/.zshrc ~/.zlogin; do
-        if [ -f "$file" ]; then
-            if grep -l "^[^#].*.nix-profile" "$file"; then
-                failure <<EOF
-I found a reference to a ".nix-profile" in $file.
-This has a high chance of breaking a new nix installation. It was most
-likely put there by a previous Nix installer.
-
-Please remove this reference and try running this again. You should
-also look for similar references in:
-
- - ~/.bash_profile
- - ~/.bash_login
- - ~/.profile
-
-or other shell init files that you may have.
-
-$(uninstall_directions)
-EOF
-            fi
-        fi
-    done
-
-    if [ -d /nix/store ] || [ -d /nix/var ]; then
-        failure <<EOF
-There are some relics of a previous installation of Nix at /nix, and
-this scripts assumes Nix is _not_ yet installed. Please delete the old
-Nix installation and start again.
-
-$(uninstall_directions)
-EOF
-    fi
-
-    if [ -d /etc/nix ]; then
-        failure <<EOF
-There are some relics of a previous installation of Nix at /etc/nix, and
-this scripts assumes Nix is _not_ yet installed. Please delete the old
-Nix installation and start again.
+        warning <<EOF
+Nix already appears to be installed. This installer may run into issues.
+If an error occurs, try manually uninstalling, then rerunning this script.
 
 $(uninstall_directions)
 EOF
@@ -352,7 +288,7 @@ EOF
 
     for profile_target in "${PROFILE_TARGETS[@]}"; do
         if [ -e "$profile_target$PROFILE_BACKUP_SUFFIX" ]; then
-        failure <<EOF
+            failure <<EOF
 When this script runs, it backs up the current $profile_target to
 $profile_target$PROFILE_BACKUP_SUFFIX. This backup file already exists, though.
 
@@ -364,38 +300,10 @@ in case.
 2. Take care to make sure that $profile_target$PROFILE_BACKUP_SUFFIX doesn't look like
 it has anything nix-related in it. If it does, something is probably
 quite wrong. Please open an issue or get in touch immediately.
-
-3. Take care to make sure that $profile_target doesn't look like it has
-anything nix-related in it. If it does, and $profile_target _did not_,
-run:
-
-  $ /usr/bin/sudo /bin/mv $profile_target$PROFILE_BACKUP_SUFFIX $profile_target
-
-and try again.
-EOF
-        fi
-
-        if [ -e "$profile_target" ] && grep -qi "nix" "$profile_target"; then
-            failure <<EOF
-It looks like $profile_target already has some Nix configuration in
-there. There should be no reason to run this again. If you're having
-trouble, please open an issue.
 EOF
         fi
     done
 
-    danger_paths=("$ROOT_HOME/.nix-defexpr" "$ROOT_HOME/.nix-channels" "$ROOT_HOME/.nix-profile")
-    for danger_path in "${danger_paths[@]}"; do
-        if _sudo "making sure that $danger_path doesn't exist" \
-           test -e "$danger_path"; then
-            failure <<EOF
-I found a file at $danger_path, which is a relic of a previous
-installation. You must first delete this file before continuing.
-
-$(uninstall_directions)
-EOF
-        fi
-    done
 }
 
 setup_report() {
@@ -772,9 +680,7 @@ main() {
     welcome_to_nix
     chat_about_sudo
 
-    if [ "${ALLOW_PREEXISTING_INSTALLATION:-}" = "" ]; then
-        validate_starting_assumptions
-    fi
+    validate_starting_assumptions
 
     setup_report