diff --git a/src/java/org/apache/poi/poifs/filesystem/OfficeXmlFileException.java b/src/java/org/apache/poi/poifs/filesystem/OfficeXmlFileException.java
new file mode 100644
index 000000000..b83ccd0f2
--- /dev/null
+++ b/src/java/org/apache/poi/poifs/filesystem/OfficeXmlFileException.java
@@ -0,0 +1,36 @@
+
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+        
+
+
+package org.apache.poi.poifs.filesystem;
+
+/**
+ * This exception is thrown when we try to open a file that's actually
+ *  an Office 2007+ XML file, rather than an OLE2 file (which is what
+ *  POI works with)
+ *
+ * @author Nick Burch
+ */
+
+public class OfficeXmlFileException extends IllegalArgumentException
+{
+	public OfficeXmlFileException(String s) {
+		super(s);
+	}
+}
diff --git a/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java b/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java
index 70e1c301b..16c94e2c2 100644
--- a/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java
+++ b/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java
@@ -24,6 +24,7 @@ import java.io.*;
 import java.util.*;
 
 import org.apache.poi.poifs.common.POIFSConstants;
+import org.apache.poi.poifs.filesystem.OfficeXmlFileException;
 import org.apache.poi.util.IOUtils;
 import org.apache.poi.util.IntegerField;
 import org.apache.poi.util.LittleEndian;
@@ -89,6 +90,13 @@ public class HeaderBlockReader
 
         if (signature.get() != _signature)
         {
+			// Is it one of the usual suspects?
+			if(_data[0] == 0x50 && _data[1] == 0x4b && _data[2] == 0x03 &&
+					_data[3] == 0x04) {
+				throw new OfficeXmlFileException("The supplied data appears to be in the Office 2007+ XML. POI only supports OLE2 Office documents");
+			}
+
+			// Give a generic error
             throw new IOException("Invalid header signature; read "
                                   + signature.get() + ", expected "
                                   + _signature);
diff --git a/src/testcases/org/apache/poi/hssf/data/sample.xlsx b/src/testcases/org/apache/poi/hssf/data/sample.xlsx
new file mode 100644
index 000000000..2eb36ee2a
Binary files /dev/null and b/src/testcases/org/apache/poi/hssf/data/sample.xlsx differ
diff --git a/src/testcases/org/apache/poi/poifs/filesystem/TestOffice2007XMLException.java b/src/testcases/org/apache/poi/poifs/filesystem/TestOffice2007XMLException.java
new file mode 100644
index 000000000..db8607d37
--- /dev/null
+++ b/src/testcases/org/apache/poi/poifs/filesystem/TestOffice2007XMLException.java
@@ -0,0 +1,50 @@
+
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+        
+
+package org.apache.poi.poifs.filesystem;
+
+import junit.framework.TestCase;
+import java.io.*;
+
+/**
+ * Class to test that POIFS complains when given an Office 2007 XML document
+ *
+ * @author Marc Johnson
+ */
+
+public class TestOffice2007XMLException extends TestCase
+{
+	public String dirname;
+
+	public void setUp() {
+		dirname = System.getProperty("HSSF.testdata.path");
+	}
+
+	public void testXMLException() throws IOException
+	{
+		FileInputStream in = new FileInputStream(dirname + "/sample.xlsx");
+
+		try {
+			new POIFSFileSystem(in);
+			fail();
+		} catch(OfficeXmlFileException e) {
+			// Good
+		}
+	}
+}