diff --git a/src/documentation/content/xdocs/status.xml b/src/documentation/content/xdocs/status.xml
index b1790bf74..96acff77e 100644
--- a/src/documentation/content/xdocs/status.xml
+++ b/src/documentation/content/xdocs/status.xml
@@ -34,6 +34,7 @@
 
     <changes>
         <release version="3.8-beta4" date="2011-??-??">
+           <action dev="poi-developers" type="fix">51535 - correct signed vs unsigned short reading in NDocumentInputStream</action>
            <action dev="poi-developers" type="add">51634 - support SXSSF streaming from templates</action>
            <action dev="poi-developers" type="add">initial support for XSLF usermodel API</action>
            <action dev="poi-developers" type="fix">51187 - fixed OPCPackage to correctly handle self references</action>
diff --git a/src/java/org/apache/poi/poifs/filesystem/NDocumentInputStream.java b/src/java/org/apache/poi/poifs/filesystem/NDocumentInputStream.java
index cb4f7ffe7..1db8975d2 100644
--- a/src/java/org/apache/poi/poifs/filesystem/NDocumentInputStream.java
+++ b/src/java/org/apache/poi/poifs/filesystem/NDocumentInputStream.java
@@ -275,7 +275,10 @@ public final class NDocumentInputStream extends DocumentInputStream {
 
    @Override
    public short readShort() {
-      return (short) readUShort();
+      checkAvaliable(SIZE_SHORT);
+      byte[] data = new byte[SIZE_SHORT];
+      readFully(data, 0, SIZE_SHORT);
+      return LittleEndian.getShort(data);
    }
 
    @Override
@@ -291,7 +294,7 @@ public final class NDocumentInputStream extends DocumentInputStream {
 		checkAvaliable(SIZE_SHORT);
       byte[] data = new byte[SIZE_SHORT];
       readFully(data, 0, SIZE_SHORT);
-      return LittleEndian.getShort(data);
+      return LittleEndian.getUShort(data);
 	}
 
    @Override
diff --git a/src/testcases/org/apache/poi/hssf/usermodel/TestBugs.java b/src/testcases/org/apache/poi/hssf/usermodel/TestBugs.java
index 25ad94e35..d53e50783 100644
--- a/src/testcases/org/apache/poi/hssf/usermodel/TestBugs.java
+++ b/src/testcases/org/apache/poi/hssf/usermodel/TestBugs.java
@@ -2144,9 +2144,9 @@ if(1==2) {
     }
     
     /**
-     * Large row numbers
+     * Large row numbers and NPOIFS vs POIFS
      */
-    public void DISABLEDtest51535() throws Exception {
+    public void test51535() throws Exception {
        byte[] data = HSSFITestDataProvider.instance.getTestDataFileContent("51535.xls");
        
        HSSFWorkbook wbPOIFS = new HSSFWorkbook(new POIFSFileSystem(