diff --git a/kmmessage.cpp b/kmmessage.cpp
index 140a2fc54..9580fe026 100644
--- a/kmmessage.cpp
+++ b/kmmessage.cpp
@@ -15,6 +15,7 @@ using KMail::MessageProperty;
 #include "objecttreeparser.h"
 using KMail::ObjectTreeParser;
 #include "kmfolderindex.h"
+#include "kmmsgdict.h"
 #include "undostack.h"
 #include "kmversion.h"
 #include <libkpimidentities/identity.h>
@@ -208,7 +209,11 @@ QCString KMMessage::id() const
 //-----------------------------------------------------------------------------
 void KMMessage::setMsgSerNum(unsigned long newMsgSerNum)
 {
+  unsigned long oldMsgSerNum = getMsgSerNum();
   MessageProperty::setSerialCache( this, newMsgSerNum );
+
+  if ( newMsgSerNum && oldMsgSerNum )
+    kmkernel->msgDict()->replace( newMsgSerNum, this );
 }
 
 
diff --git a/kmmsgdict.cpp b/kmmsgdict.cpp
index 15883ce0d..315f36d19 100644
--- a/kmmsgdict.cpp
+++ b/kmmsgdict.cpp
@@ -211,6 +211,28 @@ unsigned long KMMsgDict::insert(const KMMsgBase *msg, int index)
 
 //-----------------------------------------------------------------------------
 
+void KMMsgDict::replace(unsigned long msgSerNum,
+		       const KMMsgBase *msg, int index)
+{
+  KMFolderIndex* folder = static_cast<KMFolderIndex*>( msg->storage() );
+  if ( folder && index == -1 )
+    index = folder->find( msg );
+
+  remove( msgSerNum );
+  KMMsgDictEntry *entry = new KMMsgDictEntry( folder->folder(), index );
+  dict->insert( (long)msgSerNum, entry );
+
+  KMMsgDictREntry *rentry = folder->rDict();
+  if (!rentry) {
+    rentry = new KMMsgDictREntry();
+    folder->setRDict(rentry);
+  }
+  rentry->set(index, entry);
+
+}
+
+//-----------------------------------------------------------------------------
+
 void KMMsgDict::remove(unsigned long msgSerNum)
 {
   long key = (long)msgSerNum;
diff --git a/kmmsgdict.h b/kmmsgdict.h
index d2da33494..b4c5f48f1 100644
--- a/kmmsgdict.h
+++ b/kmmsgdict.h
@@ -31,6 +31,10 @@ public:
    * serial number. */
   unsigned long insert(const KMMsgBase *msg, int index = -1);
 
+  /** Set the serial number of @p msg to @p msgSerNum */
+  void replace(unsigned long msgSerNum,
+	       const KMMsgBase *msg, int index = -1);
+
   /** Removes a message. */
   void remove(unsigned long msgSerNum);