diff --git a/backup.sh b/backup.sh
index df742a3..10e29ae 100755
--- a/backup.sh
+++ b/backup.sh
@@ -16,6 +16,35 @@
 #ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCsCm6f5JOlKDbZMiQ6rXvU35QU4Gs/WKKlZymXtFxPhK5jBoZskQjNhfsr+peuhnZ1y+04L9qEBkN3jN0ThROaRaKSFVWfnMnij7pEB0bmJRxDmkQsHL7YsAm6tPn8116tt9m9ASPYE5RpnaDGtxTP7uXa42URvwXdvWY618tdX4z39JG9f85KYexhwRbhaBMLnSPH6JKCKu1tTBwr7oEbuhLFrFXQwqWRip/oN/6/eSxnIrwaey1GM+CdNfeGh/0OeQJ4XIUas2WbgiQRw6Dkxo32FeFS5LVaOYWRys6W3Znw9a9yOYImjJ8WUmiwSeN2bksUizNBNA1HBhoKGM5b root@alphys
 #
 
+declare -ra required_tools=(
+  rsync
+  ssh
+  zfs
+  zpool
+  awk
+)
+for tool in "${required_tools[@]}"; do
+  if ! command -v "$tool" >/dev/null 2>&1; then
+    echo "Mangler påkrevd verktøy: $tool"
+    exit 1
+  fi
+done
+
+if [ "$(id -u)" -ne 0 ]; then
+  echo "Må kjøres som root!"
+  exit 1
+fi
+
+# 5.1 er minimum pga. wait '-p' flagget.
+declare -r minimum_bash_major_version="5"
+declare -r minimum_bash_minor_version="1"
+if [ \
+  "${BASH_VERSINFO[0]}" -lt "$minimum_bash_major_version" ] || \
+  { [ "${BASH_VERSINFO[0]}" -eq "$minimum_bash_major_version" ] && \
+    [ "${BASH_VERSINFO[1]}" -lt "$minimum_bash_minor_version" ]; }; then
+  echo "Må kjøres med bash versjon $minimum_bash_major_version eller nyere!"
+  exit 1
+fi
 
 echo "PVV; hjemmelaget backupscript (\$ git commit sha: $(cd /backupz && git rev-parse HEAD) \$)"
 echo