diff --git a/source/java/org/alfresco/repo/content/AbstractContentWriter.java b/source/java/org/alfresco/repo/content/AbstractContentWriter.java
index b49f195d9d..0d26e7411b 100644
--- a/source/java/org/alfresco/repo/content/AbstractContentWriter.java
+++ b/source/java/org/alfresco/repo/content/AbstractContentWriter.java
@@ -617,7 +617,7 @@ public abstract class AbstractContentWriter extends AbstractContentAccessor impl
     private void doGuessMimetype(String filename)
     {
         String mimetype;
-        if (filename.startsWith(MimetypeMap.MACOS_RESOURCE_FORK_FILE_NAME_PREFIX))
+        if (filename != null && filename.startsWith(MimetypeMap.MACOS_RESOURCE_FORK_FILE_NAME_PREFIX))
         {
             mimetype = MimetypeMap.MIMETYPE_APPLEFILE;
         }