diff -Nur poi.original/src/java/org/apache/poi/hssf/model/Workbook.java poi.patched/src/java/org/apache/poi/hssf/model/Workbook.java
--- poi.original/src/java/org/apache/poi/hssf/model/Workbook.java	2004-07-28 20:06:32.000000000 +0700
+++ poi.patched/src/java/org/apache/poi/hssf/model/Workbook.java	2005-03-16 17:42:06.264563855 +0600
@@ -29,6 +29,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
+import java.io.UnsupportedEncodingException;
 
 /**
  * Low level model implementation of a Workbook.  Provides creational methods
@@ -1963,6 +1964,7 @@
         maxformatid = maxformatid >= (short) 0xa4 ? (short) ( maxformatid + 1 ) : (short) 0xa4; //Starting value from M$ empiracle study.
         rec.setIndexCode( maxformatid );
         rec.setFormatStringLength( (byte) format.length() );
+        rec.setUnicodeFlag(isUnicodeFormat(format));
         rec.setFormatString( format );
 
         int pos = 0;
@@ -1974,6 +1976,17 @@
         return maxformatid;
     }
 
+  /**
+   * @param format
+   * @return true if format is Unicode.
+   */
+  private boolean isUnicodeFormat(final String format) {
+    try {
+      return !format.equals(new String(format.getBytes("ISO-8859-1"), "ISO-8859-1"));
+    } catch (UnsupportedEncodingException e) {
+      return true;
+    }
+  }
 
     /**
      * Returns the first occurance of a record matching a particular sid.