diff --git a/src/java/org/apache/cassandra/service/ReadResponseResolver.java b/src/java/org/apache/cassandra/service/ReadResponseResolver.java
index 798fb03b33..baa3df9cc4 100644
--- a/src/java/org/apache/cassandra/service/ReadResponseResolver.java
+++ b/src/java/org/apache/cassandra/service/ReadResponseResolver.java
@@ -27,6 +27,7 @@ import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ConcurrentMap;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -44,7 +45,7 @@ public class ReadResponseResolver implements IResponseResolver<Row>
 {
 	private static Logger logger_ = LoggerFactory.getLogger(ReadResponseResolver.class);
     private final String table;
-    private final Map<Message, ReadResponse> results = new NonBlockingHashMap<Message, ReadResponse>();
+    private final ConcurrentMap<Message, ReadResponse> results = new NonBlockingHashMap<Message, ReadResponse>();
     private DecoratedKey key;
     private ByteBuffer digest;