diff --git a/packages/backend/src/db/queries/users.ts b/packages/backend/src/db/queries/users.ts
index 67774e2..bd034c6 100644
--- a/packages/backend/src/db/queries/users.ts
+++ b/packages/backend/src/db/queries/users.ts
@@ -2,7 +2,12 @@ import { type IconStyle, User, type UserRecord } from "@sprint/shared";
 import { eq } from "drizzle-orm";
 import { db } from "../client";
 
-export async function createUser(name: string, username: string, passwordHash: string, avatarURL?: string) {
+export async function createUser(
+    name: string,
+    username: string,
+    passwordHash: string,
+    avatarURL?: string | null,
+) {
     const [user] = await db.insert(User).values({ name, username, passwordHash, avatarURL }).returning();
     return user;
 }
diff --git a/packages/shared/src/api-schemas.ts b/packages/shared/src/api-schemas.ts
index 0cf513a..425bfcb 100644
--- a/packages/shared/src/api-schemas.ts
+++ b/packages/shared/src/api-schemas.ts
@@ -43,7 +43,7 @@ export const RegisterRequestSchema = z.object({
         .regex(/[A-Z]/, "Password must contain an uppercase letter")
         .regex(/[a-z]/, "Password must contain a lowercase letter")
         .regex(/[0-9]/, "Password must contain a number"),
-    avatarURL: z.string().url().nullable(),
+    avatarURL: z.string().url().nullable().optional(),
 });
 
 export type RegisterRequest = z.infer<typeof RegisterRequestSchema>;