diff --git a/api/index.php b/api/index.php
index 3c82bb6..878c818 100644
--- a/api/index.php
+++ b/api/index.php
@@ -120,7 +120,7 @@ switch ($VARS['action']) {
     case "addmachine":
         dieWithoutRole(Roles::ROLE_ADDEDIT);
         if (empty($VARS['id'])) {
-            sendError("nomachineid");
+            $VARS['id'] = Machine::generateId();
         }
         if ($database->has('machines', ['machineid' => $VARS['id']])) {
             sendError("", "A machine with that ID already exists.");
@@ -157,7 +157,7 @@ switch ($VARS['action']) {
         if ($database->error()[1] != 0) {
             sendError("dberror", $database->error()[2]);
         }
-        exit(json_encode(["status" => "OK"]));
+        exit(json_encode(["status" => "OK", "id" => $data['machineid']]));
         break;
     case "addhistory":
         dieWithoutRole([Roles::ROLE_ADDEDIT, Roles::ROLE_ADDHIST]);
diff --git a/machine.php b/machine.php
index 2767fa4..2605065 100644
--- a/machine.php
+++ b/machine.php
@@ -118,4 +118,20 @@ class Machine {
 
         $database->insert('components', ['serial' => $serial, 'typeid' => $type, 'tested' => $tested, 'notes' => $notes, 'capacity' => $capacity, 'model' => $model, 'machineid' => $this->machineid]);
     }
+
+    /**
+     * Generate a random machine ID number that is not in use.
+     * @global $database
+     * @param int $min Optional minimum number.
+     * @param int $max Optional maximum number.
+     * @return int
+     */
+    public static function generateId(int $min = 1000000000, int $max = 9999999999): int {
+        global $database;
+        $id = random_int(1000000000, 9999999999);
+        while ($database->has('machines', ['machineid' => $id])) {
+            $id = random_int(1000000000, 9999999999);
+        }
+        return $id;
+    }
 }