diff --git a/src/p_doors.cpp b/src/p_doors.cpp
index 7ccfa54b1..0c815313f 100644
--- a/src/p_doors.cpp
+++ b/src/p_doors.cpp
@@ -232,9 +232,13 @@ void DDoor::Tick ()
 //
 // [RH] DoorSound: Plays door sound depending on direction and speed
 //
+// If curseq is non-NULL, then it will check if the desired sound sequence
+// will result in a different command stream than the current one. If not,
+// then it does nothing.
+//
 //============================================================================
 
-void DDoor::DoorSound (bool raise) const
+void DDoor::DoorSound(bool raise, DSeqNode *curseq) const
 {
 	int choice;
 
@@ -253,11 +257,17 @@ void DDoor::DoorSound (bool raise) const
 
 	if (m_Sector->seqType >= 0)
 	{
-		SN_StartSequence (m_Sector, CHAN_CEILING, m_Sector->seqType, SEQ_DOOR, choice);
+		if (curseq == NULL || !SN_AreModesSame(m_Sector->seqType, SEQ_DOOR, choice, curseq->GetModeNum()))
+		{
+			SN_StartSequence(m_Sector, CHAN_CEILING, m_Sector->seqType, SEQ_DOOR, choice);
+		}
 	}
 	else if (m_Sector->SeqName != NAME_None)
 	{
-		SN_StartSequence (m_Sector, CHAN_CEILING, m_Sector->SeqName, choice);
+		if (curseq == NULL || !SN_AreModesSame(m_Sector->SeqName, choice, curseq->GetModeNum()))
+		{
+			SN_StartSequence(m_Sector, CHAN_CEILING, m_Sector->SeqName, choice);
+		}
 	}
 	else
 	{
@@ -318,7 +328,10 @@ void DDoor::DoorSound (bool raise) const
 			}
 			break;
 		}
-		SN_StartSequence (m_Sector, CHAN_CEILING, snd, choice);
+		if (curseq == NULL || !SN_AreModesSame(snd, choice, curseq->GetModeNum()))
+		{
+			SN_StartSequence(m_Sector, CHAN_CEILING, snd, choice);
+		}
 	}
 }
 
@@ -450,15 +463,8 @@ bool EV_DoDoor (DDoor::EVlDoor type, line_t *line, AActor *thing,
 
 						door->m_Direction = -1;	// start going down immediately
 
-						// [RH] If this sector doesn't have a specific sound
-						// attached to it, start the door close sequence.
-						// Otherwise, just let the current one continue.
-						// FIXME: This should be check if the sound sequence has separate up/down
-						// paths, not if it was manually set.
-						if ((sec->seqType < 0 && sec->SeqName == NAME_None) || SN_CheckSequence(sec, CHAN_CEILING) == NULL)
-						{
-							door->DoorSound (false);
-						}
+						// Start the door close sequence.
+						door->DoorSound(false, SN_CheckSequence(sec, CHAN_CEILING));
 						return true;
 					}
 					else
diff --git a/src/p_spec.h b/src/p_spec.h
index 54a1b7a0f..47987d383 100644
--- a/src/p_spec.h
+++ b/src/p_spec.h
@@ -531,7 +531,7 @@ protected:
 
 	int			m_LightTag;
 
-	void DoorSound (bool raise) const;
+	void DoorSound (bool raise, class DSeqNode *curseq=NULL) const;
 
 	friend bool	EV_DoDoor (DDoor::EVlDoor type, line_t *line, AActor *thing,
 						   int tag, int speed, int delay, int lock,
diff --git a/src/s_sndseq.cpp b/src/s_sndseq.cpp
index 0df036662..9ba713dcb 100644
--- a/src/s_sndseq.cpp
+++ b/src/s_sndseq.cpp
@@ -839,10 +839,7 @@ static bool TwiddleSeqNum (int &sequence, seqtype_t type)
 		}
 	}
 
-	if (sequence == -1 || Sequences[sequence] == NULL)
-		return false;
-	else
-		return true;
+	return ((size_t)sequence < Sequences.Size() && Sequences[sequence] != NULL);
 }
 
 DSeqNode *SN_StartSequence (AActor *actor, int sequence, seqtype_t type, int modenum, bool nostop)
@@ -892,7 +889,7 @@ DSeqNode *SN_StartSequence (FPolyObj *poly, int sequence, seqtype_t type, int mo
 
 DSeqNode *SN_StartSequence (AActor *actor, const char *seqname, int modenum)
 {
-	int seqnum = FindSequence (seqname);
+	int seqnum = FindSequence(seqname);
 	if (seqnum >= 0)
 	{
 		return SN_StartSequence (actor, seqnum, SEQ_NOTRANS, modenum);
@@ -902,7 +899,7 @@ DSeqNode *SN_StartSequence (AActor *actor, const char *seqname, int modenum)
 
 DSeqNode *SN_StartSequence (AActor *actor, FName seqname, int modenum)
 {
-	int seqnum = FindSequence (seqname);
+	int seqnum = FindSequence(seqname);
 	if (seqnum >= 0)
 	{
 		return SN_StartSequence (actor, seqnum, SEQ_NOTRANS, modenum);
@@ -912,7 +909,7 @@ DSeqNode *SN_StartSequence (AActor *actor, FName seqname, int modenum)
 
 DSeqNode *SN_StartSequence (sector_t *sec, int chan, const char *seqname, int modenum)
 {
-	int seqnum = FindSequence (seqname);
+	int seqnum = FindSequence(seqname);
 	if (seqnum >= 0)
 	{
 		return SN_StartSequence (sec, chan, seqnum, SEQ_NOTRANS, modenum);
@@ -922,7 +919,7 @@ DSeqNode *SN_StartSequence (sector_t *sec, int chan, const char *seqname, int mo
 
 DSeqNode *SN_StartSequence (sector_t *sec, int chan, FName seqname, int modenum)
 {
-	int seqnum = FindSequence (seqname);
+	int seqnum = FindSequence(seqname);
 	if (seqnum >= 0)
 	{
 		return SN_StartSequence (sec, chan, seqnum, SEQ_NOTRANS, modenum);
@@ -932,7 +929,7 @@ DSeqNode *SN_StartSequence (sector_t *sec, int chan, FName seqname, int modenum)
 
 DSeqNode *SN_StartSequence (FPolyObj *poly, const char *seqname, int modenum)
 {
-	int seqnum = FindSequence (seqname);
+	int seqnum = FindSequence(seqname);
 	if (seqnum >= 0)
 	{
 		return SN_StartSequence (poly, seqnum, SEQ_NOTRANS, modenum);
@@ -942,20 +939,18 @@ DSeqNode *SN_StartSequence (FPolyObj *poly, const char *seqname, int modenum)
 
 static int FindSequence (const char *searchname)
 {
-	FName seqname (searchname, true);
+	FName seqname(searchname, true);
 
 	if (seqname != NAME_None)
 	{
-		return FindSequence (seqname);
+		return FindSequence(seqname);
 	}
 	return -1;
 }
 
 static int FindSequence (FName seqname)
 {
-	int i;
-
-	for (i = Sequences.Size(); i-- > 0; )
+	for (int i = Sequences.Size(); i-- > 0; )
 	{
 		if (Sequences[i] != NULL && seqname == Sequences[i]->SeqName)
 		{
@@ -1216,7 +1211,7 @@ void DSeqNode::Tick ()
 			{ // Completely transfer control to the choice matching m_ModeNum.
 			  // If no match is found, then just advance to the next command
 			  // in this sequence, which should be SS_CMD_END.
-				int numchoices = GetData(*m_SequencePtr++);
+ 				int numchoices = GetData(*m_SequencePtr++);
 				int i;
 
 				for (i = 0; i < numchoices; ++i)
@@ -1351,6 +1346,93 @@ void DSeqNode::ChangeData (int seqOffset, int delayTics, float volume, FSoundID
 	m_CurrentSoundID = currentSoundID;
 }
 
+//==========================================================================
+//
+// FindMode
+//
+// Finds the sequence this sequence and mode combination selects.
+//
+//==========================================================================
+
+static int FindMode(int seqnum, int mode)
+{
+	if (seqnum <= 0)
+	{ // Sequence does not exist.
+		return seqnum;
+	}
+	FSoundSequence *seq = Sequences[seqnum];
+	if (GetCommand(seq->Script[0]) != SS_CMD_SELECT)
+	{ // This sequence doesn't select any others.
+		return seqnum;
+	}
+	// Search for the desired mode amongst the selections
+	int nummodes = GetData(seq->Script[0]);
+	for (int i = 0; i < nummodes; ++i)
+	{
+		if (seq->Script[1 + i*2] == mode)
+		{
+			return FindSequence(ENamedName(seq->Script[1 + i*2 + 1]));
+		}
+	}
+	// The mode isn't selected, which means it stays on this sequence.
+	return seqnum;
+}
+
+//==========================================================================
+//
+// FindModeDeep
+//
+// Finds the final sequence this sequence and mode combination selects.
+//
+//==========================================================================
+
+static int FindModeDeep(int seqnum, int mode)
+{
+	int newseqnum = FindMode(seqnum, mode);
+
+	while (newseqnum != seqnum)
+	{
+		seqnum = newseqnum;
+		newseqnum = FindMode(seqnum, mode);
+	}
+	return seqnum;
+}
+
+//==========================================================================
+//
+// SN_AreModesSame
+//
+// Returns true if mode1 and mode2 represent the same sequence.
+//
+//==========================================================================
+
+bool SN_AreModesSame(int seqnum, seqtype_t type, int mode1, int mode2)
+{
+	if (mode1 == mode2)
+	{ // Obviously they're the same.
+		return true;
+	}
+	if (TwiddleSeqNum(seqnum, type))
+	{
+		int mode1seq = FindModeDeep(seqnum, mode1);
+		int mode2seq = FindModeDeep(seqnum, mode2);
+		return mode1seq == mode2seq;
+	}
+	// The sequence doesn't exist, so that makes both modes equally nonexistant.
+	return true;
+}
+
+bool SN_AreModesSame(const char *name, int mode1, int mode2)
+{
+	int seqnum = FindSequence(name);
+	if (seqnum >= 0)
+	{
+		return SN_AreModesSame(seqnum, SEQ_NOTRANS, mode1, mode2);
+	}
+	// The sequence doesn't exist, so that makes both modes equally nonexistant.
+	return true;
+}
+
 //==========================================================================
 //
 // CCMD playsequence
diff --git a/src/s_sndseq.h b/src/s_sndseq.h
index efadc0565..41035fb1d 100644
--- a/src/s_sndseq.h
+++ b/src/s_sndseq.h
@@ -26,6 +26,7 @@ public:
 	void Tick ();
 	void ChangeData (int seqOffset, int delayTics, float volume, FSoundID currentSoundID);
 	void AddChoice (int seqnum, seqtype_t type);
+	int GetModeNum() const { return m_ModeNum; }
 	FName GetSequenceName() const;
 	static void StaticMarkHead() { GC::Mark(SequenceListHead); }
 
@@ -89,6 +90,8 @@ DSeqNode *SN_CheckSequence (sector_t *sector, int chan);
 void SN_StopSequence (AActor *mobj);
 void SN_StopSequence (sector_t *sector, int chan);
 void SN_StopSequence (FPolyObj *poly);
+bool SN_AreModesSame(int sequence, seqtype_t type, int mode1, int mode2);
+bool SN_AreModesSame(const char *name, int mode1, int mode2);
 void SN_UpdateActiveSequences (void);
 ptrdiff_t SN_GetSequenceOffset (int sequence, SDWORD *sequencePtr);
 void SN_DoStop (void *);