diff --git a/src/main/java/com/solab/iso8583/IsoMessage.java b/src/main/java/com/solab/iso8583/IsoMessage.java
index 42d3457..21f8670 100644
--- a/src/main/java/com/solab/iso8583/IsoMessage.java
+++ b/src/main/java/com/solab/iso8583/IsoMessage.java
@@ -373,6 +373,11 @@ public class IsoMessage {
     			}
     		}
     	} else {
+            ByteArrayOutputStream bout2 = null;
+            if (forceStringEncoding) {
+                bout2 = bout;
+                bout = new ByteArrayOutputStream();
+            }
             int pos = 0;
             int lim = bs.size() / 4;
             for (int i = 0; i < lim; i++) {
@@ -387,6 +392,15 @@ public class IsoMessage {
                     nibble |= 1;
                 bout.write(HEX[nibble]);
             }
+            if (forceStringEncoding) {
+                final String _hb = new String(bout.toByteArray());
+                bout = bout2;
+                try {
+                    bout.write(_hb.getBytes(encoding));
+                } catch (IOException ignore) {
+                    //never happen
+                }
+            }
     	}
 
     	//Fields
diff --git a/src/main/java/com/solab/iso8583/MessageFactory.java b/src/main/java/com/solab/iso8583/MessageFactory.java
index 1c02a70..86b177a 100644
--- a/src/main/java/com/solab/iso8583/MessageFactory.java
+++ b/src/main/java/com/solab/iso8583/MessageFactory.java
@@ -328,7 +328,7 @@ public class MessageFactory<T extends IsoMessage> {
 			try {
                 final byte[] bitmapBuffer;
                 if (forceStringEncoding) {
-                    byte[] _bb = HexCodec.hexDecode(new String(buf, isoHeaderLength+4, 16, encoding));
+                    byte[] _bb = new String(buf, isoHeaderLength+4, 16, encoding).getBytes();
                     bitmapBuffer = new byte[36+isoHeaderLength];
                     System.arraycopy(_bb, 0, bitmapBuffer, 4+isoHeaderLength, 16);
                 } else {
@@ -358,7 +358,7 @@ public class MessageFactory<T extends IsoMessage> {
 						throw new ParseException("Insufficient length for secondary bitmap", minlength);
 					}
                     if (forceStringEncoding) {
-                        byte[] _bb = HexCodec.hexDecode(new String(buf, isoHeaderLength+4, 16, encoding));
+                        byte[] _bb = new String(buf, isoHeaderLength+4, 16, encoding).getBytes();
                         System.arraycopy(_bb, 0, bitmapBuffer, 20+isoHeaderLength, 16);
                     }
 					for (int i = isoHeaderLength + 20; i < isoHeaderLength + 36; i++) {