diff --git a/src/java/org/apache/poi/poifs/filesystem/NPOIFSMiniStore.java b/src/java/org/apache/poi/poifs/filesystem/NPOIFSMiniStore.java
index a34e97efd0..f2d0b5efd2 100644
--- a/src/java/org/apache/poi/poifs/filesystem/NPOIFSMiniStore.java
+++ b/src/java/org/apache/poi/poifs/filesystem/NPOIFSMiniStore.java
@@ -50,7 +50,7 @@ public class NPOIFSMiniStore extends BlockStore
        this._header = header;
        this._root = root;
        
-       this._mini_stream = new NPOIFSStream(filesystem);
+       this._mini_stream = new NPOIFSStream(filesystem, root.getStartBlock());
     }
     
     /**
@@ -70,7 +70,9 @@ public class NPOIFSMiniStore extends BlockStore
        ByteBuffer dataBlock = it.next();
        
        // Skip forward to the right place
-       dataBlock.position(bigBlockOffset);
+       dataBlock.position(
+             dataBlock.position() + bigBlockOffset
+       );
        
        // All done
        return dataBlock;
diff --git a/src/testcases/org/apache/poi/poifs/filesystem/TestNPOIFSMiniStore.java b/src/testcases/org/apache/poi/poifs/filesystem/TestNPOIFSMiniStore.java
new file mode 100644
index 0000000000..985ad015e4
--- /dev/null
+++ b/src/testcases/org/apache/poi/poifs/filesystem/TestNPOIFSMiniStore.java
@@ -0,0 +1,250 @@
+/* ====================================================================
+   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 java.nio.ByteBuffer;
+
+import junit.framework.TestCase;
+
+import org.apache.poi.POIDataSamples;
+import org.apache.poi.poifs.common.POIFSConstants;
+
+/**
+ * Tests for the Mini Store in the NIO POIFS
+ */
+public final class TestNPOIFSMiniStore extends TestCase {
+   private static final POIDataSamples _inst = POIDataSamples.getPOIFSInstance();
+   
+   /**
+    * Check that for a given mini block, we can correctly figure
+    *  out what the next one is
+    */
+   public void testNextBlock() throws Exception {
+      // It's the same on 512 byte and 4096 byte block files!
+      NPOIFSFileSystem fsA = new NPOIFSFileSystem(_inst.getFile("BlockSize512.zvi"));
+      NPOIFSFileSystem fsB = new NPOIFSFileSystem(_inst.openResourceAsStream("BlockSize512.zvi"));
+      NPOIFSFileSystem fsC = new NPOIFSFileSystem(_inst.getFile("BlockSize4096.zvi"));
+      NPOIFSFileSystem fsD = new NPOIFSFileSystem(_inst.openResourceAsStream("BlockSize4096.zvi"));
+      for(NPOIFSFileSystem fs : new NPOIFSFileSystem[] {fsA,fsB,fsC,fsD}) {
+         NPOIFSMiniStore ministore = fs.getMiniStore();
+         
+         // 0 -> 51 is one stream
+         for(int i=0; i<50; i++) {
+            assertEquals(i+1, ministore.getNextBlock(i));
+         }
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(50));
+         
+         // 51 -> 103 is the next
+         for(int i=51; i<103; i++) {
+            assertEquals(i+1, ministore.getNextBlock(i));
+         }
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(103));
+         
+         // Then there are 3 one block ones
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(104));
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(105));
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(106));
+         
+         // 107 -> 154 is the next
+         for(int i=107; i<154; i++) {
+            assertEquals(i+1, ministore.getNextBlock(i));
+         }
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(154));
+
+         // 155 -> 160 is the next
+         for(int i=155; i<160; i++) {
+            assertEquals(i+1, ministore.getNextBlock(i));
+         }
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(160));
+         
+         // 161 -> 166 is the next
+         for(int i=161; i<166; i++) {
+            assertEquals(i+1, ministore.getNextBlock(i));
+         }
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(166));
+         
+         // 167 -> 172 is the next
+         for(int i=167; i<172; i++) {
+            assertEquals(i+1, ministore.getNextBlock(i));
+         }
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(172));
+         
+         // Now some short ones
+         assertEquals(174                        , ministore.getNextBlock(173));
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(174));
+         
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(175));
+         
+         assertEquals(177                        , ministore.getNextBlock(176));
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(177));
+         
+         assertEquals(179                        , ministore.getNextBlock(178));
+         assertEquals(180                        , ministore.getNextBlock(179));
+         assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(180));
+         
+         // 181 onwards is free
+         for(int i=181; i<fs.getBigBlockSizeDetails().getBATEntriesPerBlock(); i++) {
+            assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(i));
+         }
+      }
+   }
+
+   /**
+    * Check we get the right data back for each block
+    */
+   public void testGetBlock() throws Exception {
+      // It's the same on 512 byte and 4096 byte block files!
+      NPOIFSFileSystem fsA = new NPOIFSFileSystem(_inst.getFile("BlockSize512.zvi"));
+      NPOIFSFileSystem fsB = new NPOIFSFileSystem(_inst.openResourceAsStream("BlockSize512.zvi"));
+      NPOIFSFileSystem fsC = new NPOIFSFileSystem(_inst.getFile("BlockSize4096.zvi"));
+      NPOIFSFileSystem fsD = new NPOIFSFileSystem(_inst.openResourceAsStream("BlockSize4096.zvi"));
+      for(NPOIFSFileSystem fs : new NPOIFSFileSystem[] {fsA,fsB,fsC,fsD}) {
+         // Mini stream should be at big block zero
+         assertEquals(0, fs._get_property_table().getRoot().getStartBlock());
+         
+         // Grab the ministore
+         NPOIFSMiniStore ministore = fs.getMiniStore();
+         ByteBuffer b;
+         
+         // Runs from the start of the data section in 64 byte chungs
+         b = ministore.getBlockAt(0);
+         assertEquals((byte)0x9e, b.get());
+         assertEquals((byte)0x75, b.get());
+         assertEquals((byte)0x97, b.get());
+         assertEquals((byte)0xf6, b.get());
+         assertEquals((byte)0xff, b.get());
+         assertEquals((byte)0x21, b.get());
+         assertEquals((byte)0xd2, b.get());
+         assertEquals((byte)0x11, b.get());
+         
+         // And the next block
+         b = ministore.getBlockAt(1);
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x03, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x12, b.get());
+         assertEquals((byte)0x02, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x00, b.get());
+         
+         // Check the last data block
+         b = ministore.getBlockAt(180);
+         assertEquals((byte)0x30, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x00, b.get());
+         assertEquals((byte)0x80, b.get());
+         
+         // And the rest until the end of the big block is zeros
+         for(int i=181; i<184; i++) {
+            b = ministore.getBlockAt(i);
+            assertEquals((byte)0, b.get());
+            assertEquals((byte)0, b.get());
+            assertEquals((byte)0, b.get());
+            assertEquals((byte)0, b.get());
+            assertEquals((byte)0, b.get());
+            assertEquals((byte)0, b.get());
+            assertEquals((byte)0, b.get());
+            assertEquals((byte)0, b.get());
+         }
+      }
+   }
+   
+   /**
+    * Ask for free blocks where there are some already
+    *  to be had from the SFAT
+    */
+   public void testGetFreeBlockWithSpare() throws Exception {
+      NPOIFSFileSystem fs = new NPOIFSFileSystem(_inst.getFile("BlockSize512.zvi"));
+      NPOIFSMiniStore ministore = fs.getMiniStore();
+      
+      // Our 2nd SBAT block has spares
+      assertEquals(false, ministore.getBATBlockAndIndex(0).getBlock().hasFreeSectors());
+      assertEquals(true,  ministore.getBATBlockAndIndex(128).getBlock().hasFreeSectors());
+      
+      // First free one at 181
+      assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(181));
+      assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(182));
+      assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(183));
+      assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(184));
+      
+      // Ask, will get 181
+      assertEquals(181, ministore.getFreeBlock());
+      
+      // Ask again, will still get 181 as not written to
+      assertEquals(181, ministore.getFreeBlock());
+      
+      // Allocate it, then ask again
+      ministore.setNextBlock(181, POIFSConstants.END_OF_CHAIN);
+      assertEquals(182, ministore.getFreeBlock());
+   }
+
+   /**
+    * Ask for free blocks where no free ones exist, and so the
+    *  stream needs to be extended and another SBAT added
+    */
+   public void testGetFreeBlockWithNoneSpare() throws Exception {
+      NPOIFSFileSystem fs = new NPOIFSFileSystem(_inst.openResourceAsStream("BlockSize512.zvi"));
+      NPOIFSMiniStore ministore = fs.getMiniStore();
+      
+      // We've spare ones from 181 to 255
+      for(int i=181; i<256; i++) {
+         assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(i));
+      }
+      
+      // Check our SBAT free stuff is correct
+      assertEquals(false, ministore.getBATBlockAndIndex(0).getBlock().hasFreeSectors());
+      assertEquals(true,  ministore.getBATBlockAndIndex(128).getBlock().hasFreeSectors());
+      
+      // Allocate all the spare ones
+      for(int i=181; i<256; i++) {
+         ministore.setNextBlock(i, POIFSConstants.END_OF_CHAIN);
+      }
+      
+      // SBAT are now full, but there's only the two
+      assertEquals(false, ministore.getBATBlockAndIndex(0).getBlock().hasFreeSectors());
+      assertEquals(false, ministore.getBATBlockAndIndex(128).getBlock().hasFreeSectors());
+      try {
+         assertEquals(false, ministore.getBATBlockAndIndex(256).getBlock().hasFreeSectors());
+         fail("Should only be two SBATs");
+      } catch(IndexOutOfBoundsException e) {}
+      
+      // Now ask for a free one, will need to extend the SBAT chain
+      assertEquals(256, ministore.getFreeBlock());
+      
+      assertEquals(false, ministore.getBATBlockAndIndex(0).getBlock().hasFreeSectors());
+      assertEquals(false, ministore.getBATBlockAndIndex(128).getBlock().hasFreeSectors());
+      assertEquals(true, ministore.getBATBlockAndIndex(256).getBlock().hasFreeSectors());
+      assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(254)); // 2nd SBAT 
+      assertEquals(POIFSConstants.END_OF_CHAIN, ministore.getNextBlock(255)); // 2nd SBAT
+      assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(256)); // 3rd SBAT
+      assertEquals(POIFSConstants.UNUSED_BLOCK, ministore.getNextBlock(257)); // 3rd SBAT
+   }
+   
+   /**
+    * Test that we will extend the underlying chain of 
+    *  big blocks that make up the ministream as needed
+    */
+   public void testCreateBlockIfNeeded() throws Exception {
+      // TODO
+   }
+}