diff --git a/main/src/com/google/refine/importers/ExcelImporter.java b/main/src/com/google/refine/importers/ExcelImporter.java
index 802344bcc..4de1b3369 100644
--- a/main/src/com/google/refine/importers/ExcelImporter.java
+++ b/main/src/com/google/refine/importers/ExcelImporter.java
@@ -37,12 +37,14 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.PushbackInputStream;
 import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.poi.POIXMLDocument;
 import org.apache.poi.POIXMLException;
 import org.apache.poi.common.usermodel.Hyperlink;
 import org.apache.poi.hssf.usermodel.HSSFDateUtil;
@@ -77,10 +79,7 @@ public class ExcelImporter extends TabularImportingParserBase {
     public JSONObject createParserUIInitializationData(
             ImportingJob job, List<JSONObject> fileRecords, String format) {
         JSONObject options = super.createParserUIInitializationData(job, fileRecords, format);
-        
-        boolean xmlBased = "text/xml/xlsx".equals(format);
-        JSONUtilities.safePut(options, "xmlBased", xmlBased);
-        
+
         JSONArray sheetRecords = new JSONArray();
         JSONUtilities.safePut(options, "sheetRecords", sheetRecords);
         try {
@@ -88,8 +87,13 @@ public class ExcelImporter extends TabularImportingParserBase {
                 JSONObject firstFileRecord = fileRecords.get(0);
                 File file = ImportingUtilities.getFile(job, firstFileRecord);
                 InputStream is = new FileInputStream(file);
+
+                if (!is.markSupported()) {
+                  is = new PushbackInputStream(is, 8);
+                }
+
                 try {
-                    Workbook wb = xmlBased ?
+                    Workbook wb = POIXMLDocument.hasOOXMLHeader(is) ?
                             new XSSFWorkbook(is) :
                                 new HSSFWorkbook(new POIFSFileSystem(is));
 
@@ -136,10 +140,13 @@ public class ExcelImporter extends TabularImportingParserBase {
         JSONObject options,
         List<Exception> exceptions
     ) {
-        boolean xmlBased = JSONUtilities.getBoolean(options, "xmlBased", false);
         Workbook wb = null;
+        if (!inputStream.markSupported()) {
+          inputStream = new PushbackInputStream(inputStream, 8);
+        }
+        
         try {
-            wb = xmlBased ?
+            wb = POIXMLDocument.hasOOXMLHeader(inputStream) ?
                 new XSSFWorkbook(inputStream) :
                 new HSSFWorkbook(new POIFSFileSystem(inputStream));
         } catch (IOException e) {
diff --git a/main/webapp/modules/core/MOD-INF/controller.js b/main/webapp/modules/core/MOD-INF/controller.js
index 6e40176be..a14740dd7 100644
--- a/main/webapp/modules/core/MOD-INF/controller.js
+++ b/main/webapp/modules/core/MOD-INF/controller.js
@@ -204,14 +204,13 @@ function registerImporting() {
   IM.registerFormat("text/rdf+n3", "RDF/N3 files", "RdfTriplesParserUI", new Packages.com.google.refine.importers.RdfTripleImporter());
 
   IM.registerFormat("text/xml", "XML files", "XmlParserUI", new Packages.com.google.refine.importers.XmlImporter());
-  IM.registerFormat("text/xml/xlsx", "Excel (.xlsx) files", "ExcelParserUI", new Packages.com.google.refine.importers.ExcelImporter());
+  IM.registerFormat("binary/text/xml/xls/xlsx", "Excel files", "ExcelParserUI", new Packages.com.google.refine.importers.ExcelImporter());
   IM.registerFormat("text/xml/ods", "Open Document Format spreadsheets (.ods)", "ExcelParserUI", new Packages.com.google.refine.importers.OdsImporter());
   IM.registerFormat("text/xml/rdf", "RDF/XML files", "RdfTriplesParserUI", new Packages.com.google.refine.importers.RdfXmlTripleImporter());
   IM.registerFormat("text/json", "JSON files", "JsonParserUI", new Packages.com.google.refine.importers.JsonImporter());
   IM.registerFormat("text/marc", "MARC files", "XmlParserUI", new Packages.com.google.refine.importers.MarcImporter());
 
   IM.registerFormat("binary", "Binary files"); // generic format, no parser to handle it
-  IM.registerFormat("binary/xls", "Excel files", "ExcelParserUI", new Packages.com.google.refine.importers.ExcelImporter());
 
   IM.registerFormat("service", "Services"); // generic format, no parser to handle it
 
@@ -228,8 +227,8 @@ function registerImporting() {
   IM.registerExtension(".json", "text/json");
   IM.registerExtension(".js", "text/json");
 
-  IM.registerExtension(".xls", "binary/xls");
-  IM.registerExtension(".xlsx", "text/xml/xlsx");
+  IM.registerExtension(".xls", "binary/text/xml/xls/xlsx");
+  IM.registerExtension(".xlsx", "binary/text/xml/xls/xlsx");
 
   IM.registerExtension(".ods", "text/xml/ods");
   
@@ -250,13 +249,13 @@ function registerImporting() {
   
   IM.registerMimeType("text/rdf+n3", "text/rdf+n3");
 
-  IM.registerMimeType("application/msexcel", "binary/xls");
-  IM.registerMimeType("application/x-msexcel", "binary/xls");
-  IM.registerMimeType("application/x-ms-excel", "binary/xls");
-  IM.registerMimeType("application/vnd.ms-excel", "binary/xls");
-  IM.registerMimeType("application/x-excel", "binary/xls");
-  IM.registerMimeType("application/xls", "binary/xls");
-  IM.registerMimeType("application/x-xls", "text/xml/xlsx");
+  IM.registerMimeType("application/msexcel", "binary/text/xml/xls/xlsx");
+  IM.registerMimeType("application/x-msexcel", "binary/text/xml/xls/xlsx");
+  IM.registerMimeType("application/x-ms-excel", "binary/text/xml/xls/xlsx");
+  IM.registerMimeType("application/vnd.ms-excel", "binary/text/xml/xls/xlsx");
+  IM.registerMimeType("application/x-excel", "binary/text/xml/xls/xlsx");
+  IM.registerMimeType("application/xls", "binary/text/xml/xls/xlsx");
+  IM.registerMimeType("application/x-xls", "binary/text/xml/xls/xlsx");
   
   IM.registerMimeType("application/vnd.oasis.opendocument.spreadsheet","text/xml/ods");
 
diff --git a/main/webapp/modules/core/scripts/index/parser-interfaces/excel-parser-ui.js b/main/webapp/modules/core/scripts/index/parser-interfaces/excel-parser-ui.js
index 0c72639e2..fd24278e3 100644
--- a/main/webapp/modules/core/scripts/index/parser-interfaces/excel-parser-ui.js
+++ b/main/webapp/modules/core/scripts/index/parser-interfaces/excel-parser-ui.js
@@ -62,7 +62,6 @@ Refine.ExcelParserUI.prototype.confirmReadyToCreateProject = function() {
 
 Refine.ExcelParserUI.prototype.getOptions = function() {
   var options = {
-    xmlBased: this._config.xmlBased,
     sheets: []
   };