diff --git a/mcs/class/System.XML/System.Xml.Serialization/XmlSerializationReader.cs b/mcs/class/System.XML/System.Xml.Serialization/XmlSerializationReader.cs
index de6710af0a5f..e49e1feeca9b 100644
--- a/mcs/class/System.XML/System.Xml.Serialization/XmlSerializationReader.cs
+++ b/mcs/class/System.XML/System.Xml.Serialization/XmlSerializationReader.cs
@@ -1193,10 +1193,15 @@ protected Exception CreateMissingIXmlSerializableType (string name, string ns, s
 			throw new NotImplementedException ();
 		}
 
-		[MonoTODO]
 		protected string ReadString (string value, bool trim)
 		{
-			throw new NotImplementedException ();
+			readCount++;
+			string str = reader.ReadString ();
+			if (str != null && trim)
+				str = str.Trim();
+			if (value == null || value.Length == 0)
+				return str;
+			return value + str;
 		}
 		
 		[MonoTODO]