diff --git a/CodableFirebase/Decoder.swift b/CodableFirebase/Decoder.swift
index b1c16c2..df4ca1f 100644
--- a/CodableFirebase/Decoder.swift
+++ b/CodableFirebase/Decoder.swift
@@ -130,7 +130,7 @@ fileprivate struct _FirebaseKeyedDecodingContainer<K : CodingKey> : KeyedDecodin
     
     // MARK: - KeyedDecodingContainerProtocol Methods
     public var allKeys: [Key] {
-        return container.keys.flatMap { Key(stringValue: $0) }
+        return container.keys.compactMap { Key(stringValue: $0) }
     }
     
     public func contains(_ key: Key) -> Bool {