https://issues.apache.org/jira/browse/TILES-599
This closes #15

git-svn-id: https://svn.apache.org/repos/asf/tiles/framework/trunk@1839847 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/tiles-core/src/main/java/org/apache/tiles/preparer/factory/BasicPreparerFactory.java b/tiles-core/src/main/java/org/apache/tiles/preparer/factory/BasicPreparerFactory.java
index c9d46cd..f7d581f 100644
--- a/tiles-core/src/main/java/org/apache/tiles/preparer/factory/BasicPreparerFactory.java
+++ b/tiles-core/src/main/java/org/apache/tiles/preparer/factory/BasicPreparerFactory.java
@@ -20,8 +20,8 @@
  */
 package org.apache.tiles.preparer.factory;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.tiles.preparer.ViewPreparer;
 import org.apache.tiles.request.Request;
@@ -54,7 +54,7 @@
      * Constructor.
      */
     public BasicPreparerFactory() {
-        this.preparers = new HashMap<String, ViewPreparer>();
+        this.preparers = new ConcurrentHashMap<String, ViewPreparer>;
     }