diff --git a/src/com/esotericsoftware/kryo/serializers/DefaultSerializers.java b/src/com/esotericsoftware/kryo/serializers/DefaultSerializers.java
index 0412745fd..8e9dc5edd 100644
--- a/src/com/esotericsoftware/kryo/serializers/DefaultSerializers.java
+++ b/src/com/esotericsoftware/kryo/serializers/DefaultSerializers.java
@@ -438,7 +438,7 @@ static public class StringBufferSerializer extends Serializer<StringBuffer> {
 		}
 
 		public void write (Kryo kryo, Output output, StringBuffer object) {
-			output.writeString(object.toString());
+			output.writeString(object == null ? null : object.toString());
 		}
 
 		public StringBuffer read (Kryo kryo, Input input, Class<? extends StringBuffer> type) {
@@ -459,7 +459,7 @@ static public class StringBuilderSerializer extends Serializer<StringBuilder> {
 		}
 
 		public void write (Kryo kryo, Output output, StringBuilder object) {
-			output.writeString(object.toString());
+			output.writeString(object == null ? null : object.toString());
 		}
 
 		public StringBuilder read (Kryo kryo, Input input, Class<? extends StringBuilder> type) {