Index: pdfbox/src/main/java/org/apache/pdfbox/cos/COSStream.java
===================================================================
--- pdfbox/src/main/java/org/apache/pdfbox/cos/COSStream.java	(revision 1620300)
+++ pdfbox/src/main/java/org/apache/pdfbox/cos/COSStream.java	(working copy)
@@ -496,6 +496,10 @@
      */
     public void setFilters(COSBase filters) throws IOException
     {
+        if (unFilteredStream == null) {
+            // don't lose stream contents
+            doDecode();
+        }
         setItem(COSName.FILTER, filters);
         // kill cached filtered streams
         IOUtils.closeQuietly(filteredStream);