diff --git a/src/clients/admin/admin.ts b/src/clients/admin/admin.ts
index 1bddabd..4a34e15 100644
--- a/src/clients/admin/admin.ts
+++ b/src/clients/admin/admin.ts
@@ -444,8 +444,9 @@ export class Admin extends Base<AdminOptions> {
   }
 
   #createTopics (options: CreateTopicsOptions, callback: CallbackWithPromise<CreatedTopic[]>): void {
-    const numPartitions = options.partitions ?? 1
-    const replicationFactor = options.replicas ?? 1
+    // -1 is required if manual assignments are used. If no manual assignments are used, -1 will default to broker settings.
+    const numPartitions = options.partitions ?? -1
+    const replicationFactor = options.replicas ?? -1
     const assignments: CreateTopicsRequestTopicAssignment[] = []
     const configs = options.configs ?? []
 
diff --git a/test/clients/admin/admin.test.ts b/test/clients/admin/admin.test.ts
index 6528779..87343c2 100644
--- a/test/clients/admin/admin.test.ts
+++ b/test/clients/admin/admin.test.ts
@@ -439,8 +439,6 @@ test('createTopics using assignments', async t => {
   // Create a topic with a single partition - leader will be automatically assigned
   const created = await admin.createTopics({
     topics: [topicName],
-    partitions: -1,
-    replicas: -1,
     assignments: brokerIds.map((brokerId, i) => ({ partition: i, brokers: [brokerId] }))
   })