diff --git a/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift b/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift
index 0faa99e25f7..34f52a60a28 100644
--- a/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift
+++ b/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift
@@ -13,6 +13,7 @@
 // limitations under the License.
 
 import FirebaseCoreInternal
+import Foundation
 
 private let kFiveMinutes = 5 * 60.0