diff --git a/ooxml/POIXMLDocument.cs b/ooxml/POIXMLDocument.cs
index c8a069c64..222f25ce0 100644
--- a/ooxml/POIXMLDocument.cs
+++ b/ooxml/POIXMLDocument.cs
@@ -68,11 +68,11 @@ private void init(OPCPackage pkg)
          *  in the event of a problem.
          * Works around shortcomings in java's this() constructor calls
          */
-        public static OPCPackage OpenPackage(String path)
+        public static OPCPackage OpenPackage(String path, bool readOnly = false)
         {
             try
             {
-                return OPCPackage.Open(path);
+                return OPCPackage.Open(path, readOnly ? PackageAccess.READ: PackageAccess.READ_WRITE);
             }
             catch (InvalidFormatException e)
             {
diff --git a/ooxml/SS/UserModel/WorkbookFactory.cs b/ooxml/SS/UserModel/WorkbookFactory.cs
index d6e97ebf6..bd81185c6 100644
--- a/ooxml/SS/UserModel/WorkbookFactory.cs
+++ b/ooxml/SS/UserModel/WorkbookFactory.cs
@@ -121,7 +121,7 @@ public static IWorkbook Create(OPCPackage pkg)
         /// <returns>IWorkbook depending on the input HSSFWorkbook or XSSFWorkbook is returned.</returns>
         /// <remarks>Your input stream MUST either support mark/reset, or
         ///  be wrapped as a {@link PushbackInputStream}!</remarks>
-        public static IWorkbook Create(Stream inputStream, bool bReadonly)
+        public static IWorkbook Create(Stream inputStream, bool readOnly)
         {
             if (inputStream.Length == 0)
                 throw new EmptyFileException();
@@ -133,7 +133,7 @@ public static IWorkbook Create(Stream inputStream, bool bReadonly)
             inputStream.Position = 0;
             if (DocumentFactoryHelper.HasOOXMLHeader(inputStream))
             {
-                return new XSSFWorkbook(OPCPackage.Open(inputStream, bReadonly));
+                return new XSSFWorkbook(OPCPackage.Open(inputStream, readOnly));
             }
             throw new InvalidFormatException("Your stream was neither an OLE2 stream, nor an OOXML stream.");
         }
diff --git a/ooxml/Util/PackageHelper.cs b/ooxml/Util/PackageHelper.cs
index 9c3acc602..df29d079a 100644
--- a/ooxml/Util/PackageHelper.cs
+++ b/ooxml/Util/PackageHelper.cs
@@ -30,12 +30,11 @@ namespace NPOI.Util
      */
     public class PackageHelper
     {
-
-        public static OPCPackage Open(Stream is1)
+        public static OPCPackage Open(Stream stream, bool readOnly = false)
         {
             try
             {
-                return OPCPackage.Open(is1);
+                return OPCPackage.Open(stream, readOnly);
             }
             catch (InvalidFormatException e)
             {
diff --git a/ooxml/XSSF/UserModel/XSSFWorkbook.cs b/ooxml/XSSF/UserModel/XSSFWorkbook.cs
index e7619bb20..2940dc72f 100644
--- a/ooxml/XSSF/UserModel/XSSFWorkbook.cs
+++ b/ooxml/XSSF/UserModel/XSSFWorkbook.cs
@@ -230,8 +230,8 @@ public XSSFWorkbook(OPCPackage pkg)
          *       pkg.close(); // gracefully closes the underlying zip file
          *   </code></pre>     
          */
-        public XSSFWorkbook(Stream is1)
-            : base(PackageHelper.Open(is1))
+        public XSSFWorkbook(Stream fileStream, bool readOnly = false)
+            : base(PackageHelper.Open(fileStream, readOnly))
         {
             BeforeDocumentRead();
 
@@ -259,8 +259,8 @@ public XSSFWorkbook(Stream is1)
          *  
          * @param file   the file to open
          */
-        public XSSFWorkbook(FileInfo file)
-            : this(OPCPackage.Open(file))
+        public XSSFWorkbook(FileInfo file, bool readOnly = false)
+            : this(OPCPackage.Open(file, readOnly? PackageAccess.READ: PackageAccess.READ_WRITE))
         {
 
         }
@@ -301,8 +301,8 @@ public XSSFWorkbook(FileInfo file)
          * 
          * @param      path   the file name.
          */
-        public XSSFWorkbook(String path)
-            : this(OpenPackage(path))
+        public XSSFWorkbook(String path, bool readOnly = false)
+            : this(OpenPackage(path, readOnly))
         {
 
         }
diff --git a/openxml4Net/OPC/OPCPackage.cs b/openxml4Net/OPC/OPCPackage.cs
index 327fb58e0..6443d72cc 100644
--- a/openxml4Net/OPC/OPCPackage.cs
+++ b/openxml4Net/OPC/OPCPackage.cs
@@ -294,9 +294,9 @@ public static OPCPackage Open(FileInfo file, PackageAccess access)
          *            The InputStream to read the package from
          * @return A PackageBase object
          */
-        public static OPCPackage Open(Stream in1)
+        public static OPCPackage Open(Stream stream)
         {
-            OPCPackage pack = new ZipPackage(in1, PackageAccess.READ_WRITE);
+            OPCPackage pack = new ZipPackage(stream, PackageAccess.READ_WRITE);
             try
             {
                 if (pack.partList == null)
@@ -317,9 +317,9 @@ public static OPCPackage Open(Stream in1)
             return pack;
         }
 
-        public static OPCPackage Open(Stream in1,bool bReadonly)
+        public static OPCPackage Open(Stream stream,bool readOnly)
         {
-            OPCPackage pack = new ZipPackage(in1, bReadonly ? PackageAccess.READ : PackageAccess.READ_WRITE);
+            OPCPackage pack = new ZipPackage(stream, readOnly ? PackageAccess.READ : PackageAccess.READ_WRITE);
             if (pack.partList == null)
             {
                 pack.GetParts();