diff --git a/Src/Newtonsoft.Json/Utilities/StringUtils.cs b/Src/Newtonsoft.Json/Utilities/StringUtils.cs
index 54737636..d166b6ec 100644
--- a/Src/Newtonsoft.Json/Utilities/StringUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/StringUtils.cs
@@ -33,6 +33,7 @@ using Newtonsoft.Json.Utilities.LinqBridge;
 #else
 using System.Linq;
 #endif
+using Newtonsoft.Json.Serialization;
 
 namespace Newtonsoft.Json.Utilities
 {