diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index c7d4f7c3e..20d712642 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,3 +1,7 @@
+March 13, 2008 (Changes by Graf Zahl)
+- Fixed: Pointer substitution changed the pointers for the thinker ring list
+  resulting in a freeze.
+
 March 12, 2008
 - Fixed: DACSThinker::ActiveThinker was missing a read barrier.
 - Loading a save game now initiates a collection.
diff --git a/src/dthinker.cpp b/src/dthinker.cpp
index 37ff39543..92003bb5c 100644
--- a/src/dthinker.cpp
+++ b/src/dthinker.cpp
@@ -435,6 +435,17 @@ void DThinker::Tick ()
 {
 }
 
+void DThinker::PointerSubstitution(DObject *old, DObject *notOld)
+{
+	// Pointer substitution must not, under any circumstances, change 
+	// the linked thinker list or the game will freeze badly.
+	DThinker *next = NextThinker;
+	DThinker *prev = PrevThinker;
+	Super::PointerSubstitution(old, notOld);
+	NextThinker = next;
+	PrevThinker = prev;
+}
+
 FThinkerIterator::FThinkerIterator (const PClass *type, int statnum)
 {
 	if ((unsigned)statnum > MAX_STATNUM)
diff --git a/src/dthinker.h b/src/dthinker.h
index d6611c0c7..a9fc91e72 100644
--- a/src/dthinker.h
+++ b/src/dthinker.h
@@ -69,7 +69,8 @@ public:
 	virtual ~DThinker ();
 	virtual void Tick ();
 	virtual void PostBeginPlay ();	// Called just before the first tick
-
+	void PointerSubstitution(DObject *old, DObject *notOld);
+	
 	void ChangeStatNum (int statnum);
 
 	static void RunThinkers ();