diff --git a/lib/Db/UserMapper.php b/lib/Db/UserMapper.php
index ace1651c..2f91604c 100644
--- a/lib/Db/UserMapper.php
+++ b/lib/Db/UserMapper.php
@@ -169,4 +169,22 @@ public function getOrCreate(int $providerId, string $sub, bool $id4me = false):
 		$user->setUserId($userId);
 		return $this->insert($user);
 	}
+
+	/**
+	 * Count the total number of users provisioned by the OIDC backend.
+	 *
+	 * @return int the number of rows in the user_oidc table
+	 */
+	public function countUsers(): int {
+		$qb = $this->db->getQueryBuilder();
+
+		$qb->selectAlias($qb->func()->count('*'), 'user_count')
+			->from($this->getTableName());
+
+		$result = $qb->executeQuery();
+		$count = $result->fetchOne();
+		$result->closeCursor();
+
+		return (int)$count;
+	}
 }
diff --git a/lib/User/Backend.php b/lib/User/Backend.php
index 538276ef..a25aadd7 100644
--- a/lib/User/Backend.php
+++ b/lib/User/Backend.php
@@ -76,9 +76,13 @@ public function getBackendName(): string {
 		return Application::APP_ID;
 	}
 
+	/**
+	 * Count the number of users managed by this OIDC backend.
+	 *
+	 * @return int the number of provisioned OIDC users
+	 */
 	public function countUsers(): int {
-		$uids = $this->getUsers();
-		return count($uids);
+		return $this->userMapper->countUsers();
 	}
 
 	public function deleteUser($uid): bool {