diff --git a/Sources/DictionaryCoding/DictionaryEncoder.swift b/Sources/DictionaryCoding/DictionaryEncoder.swift
index 8d3acc5..c9402b3 100644
--- a/Sources/DictionaryCoding/DictionaryEncoder.swift
+++ b/Sources/DictionaryCoding/DictionaryEncoder.swift
@@ -675,6 +675,7 @@ extension _DictionaryEncoder {
     fileprivate func box(_ value: UInt32) -> NSObject { return NSNumber(value: value) }
     fileprivate func box(_ value: UInt64) -> NSObject { return NSNumber(value: value) }
     fileprivate func box(_ value: String) -> NSObject { return NSString(string: value) }
+    fileprivate func box(_ value: URL)    -> NSObject { return value as NSURL }
 
     fileprivate func box(_ float: Float) throws -> NSObject {
         guard !float.isInfinite && !float.isNaN else {
@@ -827,8 +828,8 @@ extension _DictionaryEncoder {
             // Respect Data encoding strategy
             return try self.box((value as! Data))
         } else if T.self == URL.self || T.self == NSURL.self {
-            // Encode URLs as single strings.
-            return self.box((value as! URL).absoluteString)
+            // Encode URLs as URLs.
+            return self.box((value as! URL))
         } else if T.self == Decimal.self || T.self == NSDecimalNumber.self {
             // DictionarySerialization can natively handle NSDecimalNumber.
             return (value as! NSDecimalNumber)