diff --git a/dumb/src/it/itrender.c b/dumb/src/it/itrender.c
index d71bdac7..4211e31f 100644
--- a/dumb/src/it/itrender.c
+++ b/dumb/src/it/itrender.c
@@ -1032,6 +1032,15 @@ static void update_retrig(DUMB_IT_SIGRENDERER *sigrenderer, IT_CHANNEL *channel)
 }
 
 
+static void update_smooth_effects_playing(IT_PLAYING *playing)
+{
+	playing->vibrato_time += playing->vibrato_n *
+		(playing->vibrato_speed << 2);
+	playing->tremolo_time += playing->tremolo_speed << 2;
+	playing->panbrello_time += playing->panbrello_speed;
+	if (playing->panbrello_waveform == 3)
+		playing->panbrello_random = (rand() % 129) - 64;
+}
 
 static void update_smooth_effects(DUMB_IT_SIGRENDERER *sigrenderer)
 {
@@ -1042,12 +1051,15 @@ static void update_smooth_effects(DUMB_IT_SIGRENDERER *sigrenderer)
 		IT_PLAYING *playing = channel->playing;
 
 		if (playing) {
-			playing->vibrato_time += playing->vibrato_n *
-			                         (playing->vibrato_speed << 2);
-			playing->tremolo_time += playing->tremolo_speed << 2;
-			playing->panbrello_time += playing->panbrello_speed;
-			if (playing->panbrello_waveform == 3)
-				playing->panbrello_random = (rand() % 129) - 64;
+			update_smooth_effects_playing(playing);
+		}
+	}
+
+	for (i = 0; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+		IT_PLAYING *playing = sigrenderer->playing[i];
+
+		if (playing) {
+			update_smooth_effects_playing(playing);
 		}
 	}
 }
@@ -1083,7 +1095,7 @@ static void update_invert_loop(IT_CHANNEL *channel, IT_SAMPLE *sample)
 
 static void update_effects(DUMB_IT_SIGRENDERER *sigrenderer)
 {
-	int i;
+	int i, j;
 
 	if (sigrenderer->globalvolslide) {
 		sigrenderer->globalvolume += sigrenderer->globalvolslide;
@@ -1167,6 +1179,10 @@ static void update_effects(DUMB_IT_SIGRENDERER *sigrenderer)
 			}
 			if (channel->playing)
 				channel->playing->channel_volume = channel->channelvolume;
+			for (j = 0; j < DUMB_IT_N_NNA_CHANNELS; j++) {
+				if (sigrenderer->playing[j] && sigrenderer->playing[j]->channel == channel)
+					sigrenderer->playing[j]->channel_volume = channel->channelvolume;
+			}
 		}
 
 		update_tremor(channel);
@@ -1177,80 +1193,121 @@ static void update_effects(DUMB_IT_SIGRENDERER *sigrenderer)
 
 		if (channel->inv_loop_speed) update_invert_loop(channel, playing ? playing->sample : NULL);
 
-		if (playing) {
-			playing->slide += channel->portamento;
+		for (j = 0; j < DUMB_IT_N_NNA_CHANNELS; j++) {
+			if (sigrenderer->playing[j] && sigrenderer->playing[j]->channel == channel) break;
+		}
+
+		if (playing || j < DUMB_IT_N_NNA_CHANNELS) {
+			if (playing) playing->slide += channel->portamento;
+			for (j = 0; j < DUMB_IT_N_NNA_CHANNELS; j++) {
+				if (sigrenderer->playing[j] && sigrenderer->playing[j]->channel == channel)
+					sigrenderer->playing[j]->slide += channel->portamento;
+			}
 
 			if (channel->okt_toneslide) {
 				if (channel->okt_toneslide--) {
-					playing->note += channel->toneslide;
-					if (playing->note >= 120) {
-						if (channel->toneslide < 0) playing->note = 0;
-						else playing->note = 119;
+					if (playing) {
+						playing->note += channel->toneslide;
+						if (playing->note >= 120) {
+							if (channel->toneslide < 0) playing->note = 0;
+							else playing->note = 119;
+						}
+					}
+					for (j = 0; j < DUMB_IT_N_NNA_CHANNELS; j++) {
+						if (sigrenderer->playing[j] && sigrenderer->playing[j]->channel == channel) {
+							IT_PLAYING *playing = sigrenderer->playing[j];
+							playing->note += channel->toneslide;
+							if (playing->note >= 120) {
+								if (channel->toneslide < 0) playing->note = 0;
+								else playing->note = 119;
+							}
+						}
 					}
 				}
 			} else if (channel->ptm_toneslide) {
 				if (--channel->toneslide_tick == 0) {
 					channel->toneslide_tick = channel->ptm_toneslide;
-					playing->note += channel->toneslide;
-					if (playing->note >= 120) {
-						if (channel->toneslide < 0) playing->note = 0;
-						else playing->note = 119;
-					}
-					channel->note = channel->truenote = playing->note;
-					if (channel->toneslide_retrig) {
-						it_playing_reset_resamplers(playing, 0);
+					if (playing) {
+						playing->note += channel->toneslide;
+						if (playing->note >= 120) {
+							if (channel->toneslide < 0) playing->note = 0;
+							else playing->note = 119;
+						}
+						channel->note = channel->truenote = playing->note;
+						if (channel->toneslide_retrig) {
+							it_playing_reset_resamplers(playing, 0);
 #ifdef END_RAMPING
-						playing->declick_stage = 0;
-						playing->declick_volume = 1.f / 256.f;
+							playing->declick_stage = 0;
+							playing->declick_volume = 1.f / 256.f;
 #endif
+						}
+					}
+					for (j = 0; j < DUMB_IT_N_NNA_CHANNELS; j++) {
+						if (sigrenderer->playing[j] && sigrenderer->playing[j]->channel == channel) {
+							IT_PLAYING *playing = sigrenderer->playing[j];
+							playing->note += channel->toneslide;
+							if (playing->note >= 120) {
+								if (channel->toneslide < 0) playing->note = 0;
+								else playing->note = 119;
+							}
+							if (channel->toneslide_retrig) {
+								it_playing_reset_resamplers(playing, 0);
+#ifdef END_RAMPING
+								playing->declick_stage = 0;
+								playing->declick_volume = 1.f / 256.f;
+#endif
+							}
+						}
 					}
 				}
 			}
 
-			if (sigrenderer->sigdata->flags & IT_LINEAR_SLIDES) {
-				if (channel->toneporta && channel->destnote < 120) {
-					int currpitch = ((playing->note - 60) << 8) + playing->slide;
-					int destpitch = (channel->destnote - 60) << 8;
-					if (currpitch > destpitch) {
-						currpitch -= channel->toneporta;
-						if (currpitch < destpitch) {
-							currpitch = destpitch;
-							channel->destnote = IT_NOTE_OFF;
-						}
-					} else if (currpitch < destpitch) {
-						currpitch += channel->toneporta;
+			if (playing) {
+				if (sigrenderer->sigdata->flags & IT_LINEAR_SLIDES) {
+					if (channel->toneporta && channel->destnote < 120) {
+						int currpitch = ((playing->note - 60) << 8) + playing->slide;
+						int destpitch = (channel->destnote - 60) << 8;
 						if (currpitch > destpitch) {
-							currpitch = destpitch;
-							channel->destnote = IT_NOTE_OFF;
+							currpitch -= channel->toneporta;
+							if (currpitch < destpitch) {
+								currpitch = destpitch;
+								channel->destnote = IT_NOTE_OFF;
+							}
+						} else if (currpitch < destpitch) {
+							currpitch += channel->toneporta;
+							if (currpitch > destpitch) {
+								currpitch = destpitch;
+								channel->destnote = IT_NOTE_OFF;
+							}
 						}
+						playing->slide = currpitch - ((playing->note - 60) << 8);
 					}
-					playing->slide = currpitch - ((playing->note - 60) << 8);
-				}
-			} else {
-				if (channel->toneporta && channel->destnote < 120) {
-					float amiga_multiplier = playing->sample->C5_speed * (1.0f / AMIGA_DIVISOR);
+				} else {
+					if (channel->toneporta && channel->destnote < 120) {
+						float amiga_multiplier = playing->sample->C5_speed * (1.0f / AMIGA_DIVISOR);
 
-					float deltanote = (float)pow(DUMB_SEMITONE_BASE, 60 - playing->note);
-					/* deltanote is 1.0 for C-5, 0.5 for C-6, etc. */
+						float deltanote = (float)pow(DUMB_SEMITONE_BASE, 60 - playing->note);
+						/* deltanote is 1.0 for C-5, 0.5 for C-6, etc. */
 
-					float deltaslid = deltanote - playing->slide * amiga_multiplier;
+						float deltaslid = deltanote - playing->slide * amiga_multiplier;
 
-					float destdelta = (float)pow(DUMB_SEMITONE_BASE, 60 - channel->destnote);
-					if (deltaslid < destdelta) {
-						playing->slide -= channel->toneporta;
-						deltaslid = deltanote - playing->slide * amiga_multiplier;
-						if (deltaslid > destdelta) {
-							playing->note = channel->destnote;
-							playing->slide = 0;
-							channel->destnote = IT_NOTE_OFF;
-						}
-					} else {
-						playing->slide += channel->toneporta;
-						deltaslid = deltanote - playing->slide * amiga_multiplier;
+						float destdelta = (float)pow(DUMB_SEMITONE_BASE, 60 - channel->destnote);
 						if (deltaslid < destdelta) {
-							playing->note = channel->destnote;
-							playing->slide = 0;
-							channel->destnote = IT_NOTE_OFF;
+							playing->slide -= channel->toneporta;
+							deltaslid = deltanote - playing->slide * amiga_multiplier;
+							if (deltaslid > destdelta) {
+								playing->note = channel->destnote;
+								playing->slide = 0;
+								channel->destnote = IT_NOTE_OFF;
+							}
+						} else {
+							playing->slide += channel->toneporta;
+							deltaslid = deltanote - playing->slide * amiga_multiplier;
+							if (deltaslid < destdelta) {
+								playing->note = channel->destnote;
+								playing->slide = 0;
+								channel->destnote = IT_NOTE_OFF;
+							}
 						}
 					}
 				}
@@ -1563,7 +1620,7 @@ static void it_retrigger_note(DUMB_IT_SIGRENDERER *sigrenderer, IT_CHANNEL *chan
 			nna = channel->playing->instrument->new_note_action;
 #endif
 
-		if ((sigdata->flags & IT_USE_INSTRUMENTS) && (channel->playing->enabled_envelopes) && channel->playing->instnum == channel->instrument) {
+		if (!(channel->playing->flags & IT_PLAYING_DEAD) && (sigdata->flags & IT_USE_INSTRUMENTS) && (channel->playing->enabled_envelopes) && channel->playing->instnum == channel->instrument) {
 			IT_PLAYING * playing = channel->playing;
 			IT_INSTRUMENT * inst = &sigdata->instrument[channel->instrument-1];
 			if ((playing->enabled_envelopes & IT_ENV_VOLUME) && (inst->volume_envelope.flags & IT_ENVELOPE_CARRY)) {
@@ -1684,7 +1741,8 @@ static void it_retrigger_note(DUMB_IT_SIGRENDERER *sigrenderer, IT_CHANNEL *chan
 	if (!flags && sigdata->flags & IT_USE_INSTRUMENTS) {
 		for (i = 0; i < DUMB_IT_N_NNA_CHANNELS; i++) {
 			IT_PLAYING * playing = sigrenderer->playing[i];
-			if (playing && (playing->enabled_envelopes) && playing->instnum == channel->instrument) {
+			if (!playing || playing->channel != channel) continue;
+			if (playing->enabled_envelopes && playing->instnum == channel->instrument) {
 				IT_INSTRUMENT * inst = &sigdata->instrument[channel->instrument-1];
 				if ((playing->enabled_envelopes & IT_ENV_VOLUME) && (inst->volume_envelope.flags & IT_ENVELOPE_CARRY)) {
 					flags |= 1;
@@ -1974,10 +2032,19 @@ static void xm_envelope_calculate_value(IT_ENVELOPE *envelope, IT_PLAYING_ENVELO
 
 extern const char xm_convert_vibrato[];
 
+const char mod_convert_vibrato[] = {
+	IT_VIBRATO_SINE,
+	IT_VIBRATO_RAMP_UP, /* this will be inverted by IT_OLD_EFFECTS */
+	IT_VIBRATO_XM_SQUARE,
+	IT_VIBRATO_XM_SQUARE
+};
+
 /* Returns 1 if a callback caused termination of playback. */
 static int process_effects(DUMB_IT_SIGRENDERER *sigrenderer, IT_ENTRY *entry, int ignore_cxx)
 {
 	DUMB_IT_SIGDATA *sigdata = sigrenderer->sigdata;
+	IT_PLAYING *playing;
+	int i;
 
 	IT_CHANNEL *channel = &sigrenderer->channel[(int)entry->channel];
 
@@ -2034,10 +2101,17 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 				break;
 
 			case IT_VOLSLIDE_VIBRATO:
-				if (channel->playing) {
-					channel->playing->vibrato_speed = channel->lastHspeed;
-					channel->playing->vibrato_depth = channel->lastHdepth;
-					channel->playing->vibrato_n++;
+				for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+					if (i < 0) playing = channel->playing;
+					else {
+						playing = sigrenderer->playing[i];
+						if (!playing || playing->channel != channel) continue;
+					}
+					if (playing) {
+						playing->vibrato_speed = channel->lastHspeed;
+						playing->vibrato_depth = channel->lastHdepth;
+						playing->vibrato_n++;
+					}
 				}
 				/* Fall through and process volume slide. */
 			case IT_VOLUME_SLIDE:
@@ -2133,15 +2207,22 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 							v = channel->lastEF;
 						channel->lastEF = v;
 					}
-					if (channel->playing) {
-						if ((v & 0xF0) == 0xF0)
-							channel->playing->slide -= (v & 15) << 4;
-						else if ((v & 0xF0) == 0xE0)
-							channel->playing->slide -= (v & 15) << 2;
-						else if (sigdata->flags & IT_WAS_A_669)
-							channel->portamento -= v << 3;
-						else
-							channel->portamento -= v << 4;
+					for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+						if (i < 0) playing = channel->playing;
+						else {
+							playing = sigrenderer->playing[i];
+							if (!playing || playing->channel != channel) continue;
+						}
+						if (playing) {
+							if ((v & 0xF0) == 0xF0)
+								playing->slide -= (v & 15) << 4;
+							else if ((v & 0xF0) == 0xE0)
+								playing->slide -= (v & 15) << 2;
+							else if (i < 0 && sigdata->flags & IT_WAS_A_669)
+								channel->portamento -= v << 3;
+							else if (i < 0)
+								channel->portamento -= v << 4;
+						}
 					}
 				}
 				break;
@@ -2168,15 +2249,22 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 							v = channel->lastEF;
 						channel->lastEF = v;
 					}
-					if (channel->playing) {
-						if ((v & 0xF0) == 0xF0)
-							channel->playing->slide += (v & 15) << 4;
-						else if ((v & 0xF0) == 0xE0)
-							channel->playing->slide += (v & 15) << 2;
-						else if (sigdata->flags & IT_WAS_A_669)
-							channel->portamento += v << 3;
-						else
-							channel->portamento += v << 4;
+					for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+						if (i < 0) playing = channel->playing;
+						else {
+							playing = sigrenderer->playing[i];
+							if (!playing || playing->channel != channel) continue;
+						}
+						if (channel->playing) {
+							if ((v & 0xF0) == 0xF0)
+								channel->playing->slide += (v & 15) << 4;
+							else if ((v & 0xF0) == 0xE0)
+								channel->playing->slide += (v & 15) << 2;
+							else if (i < 0 && sigdata->flags & IT_WAS_A_669)
+								channel->portamento += v << 3;
+							else if (i < 0)
+								channel->portamento += v << 4;
+						}
 					}
 				}
 				break;
@@ -2219,16 +2307,23 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 						if (depth == 0)
 							depth = channel->lastHdepth;
 						else {
-							if (sigdata->flags & IT_OLD_EFFECTS)
+							if (sigdata->flags & IT_OLD_EFFECTS && !(sigdata->flags & IT_WAS_A_MOD))
 								depth <<= 3;
 							else
 								depth <<= 2;
 							channel->lastHdepth = depth;
 						}
-						if (channel->playing) {
-							channel->playing->vibrato_speed = speed;
-							channel->playing->vibrato_depth = depth;
-							channel->playing->vibrato_n++;
+						for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+							if (i < 0) playing = channel->playing;
+							else {
+								playing = sigrenderer->playing[i];
+								if (!playing || playing->channel != channel) continue;
+							}
+							if (playing) {
+								playing->vibrato_speed = speed;
+								playing->vibrato_depth = depth;
+								playing->vibrato_n++;
+							}
 						}
 					}
 				}
@@ -2284,8 +2379,15 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 				else
 					channel->channelvolume = 64;
 #endif
-				if (channel->playing)
-					channel->playing->channel_volume = channel->channelvolume;
+				for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+					if (i < 0) playing = channel->playing;
+					else {
+						playing = sigrenderer->playing[i];
+						if (!playing || playing->channel != channel) continue;
+					}
+					if (playing)
+						playing->channel_volume = channel->channelvolume;
+				}
 				break;
 			case IT_CHANNEL_VOLUME_SLIDE:
 				{
@@ -2306,8 +2408,15 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 							if (channel->channelvolume > 64) channel->channelvolume = 0;
 						} else
 							break;
-						if (channel->playing)
-							channel->playing->channel_volume = channel->channelvolume;
+						for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+							if (i < 0) playing = channel->playing;
+							else {
+								playing = sigrenderer->playing[i];
+								if (!playing || playing->channel != channel) continue;
+							}
+							if (playing)
+								playing->channel_volume = channel->channelvolume;
+						}
 					}
 				}
 				break;
@@ -2460,9 +2569,16 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 							depth = channel->lastRdepth;
 						channel->lastRdepth = depth;
 					}
-					if (channel->playing) {
-						channel->playing->tremolo_speed = speed;
-						channel->playing->tremolo_depth = depth;
+					for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+						if (i < 0) playing = channel->playing;
+						else {
+							playing = sigrenderer->playing[i];
+							if (!playing || playing->channel != channel) continue;
+						}
+						if (playing) {
+							playing->tremolo_speed = speed;
+							playing->tremolo_depth = depth;
+						}
 					}
 				}
 				break;
@@ -2491,7 +2607,8 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 						case IT_S_SET_VIBRATO_WAVEFORM:
 							{
 								int waveform = effectvalue & 3;
-								if (sigdata->flags & IT_WAS_AN_XM) waveform = xm_convert_vibrato[waveform];
+								if (sigdata->flags & IT_WAS_A_MOD) waveform = mod_convert_vibrato[waveform];
+								else if (sigdata->flags & IT_WAS_AN_XM) waveform = xm_convert_vibrato[waveform];
 								channel->vibrato_waveform = waveform;
 								if (channel->playing) {
 									channel->playing->vibrato_waveform = waveform;
@@ -2503,7 +2620,8 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 						case IT_S_SET_TREMOLO_WAVEFORM:
 							{
 								int waveform = effectvalue & 3;
-								if (sigdata->flags & IT_WAS_AN_XM) waveform = xm_convert_vibrato[waveform];
+								if (sigdata->flags & IT_WAS_A_MOD) waveform = mod_convert_vibrato[waveform];
+								else if (sigdata->flags & IT_WAS_AN_XM) waveform = xm_convert_vibrato[waveform];
 								channel->tremolo_waveform = waveform;
 								if (channel->playing) {
 									channel->playing->tremolo_waveform = waveform;
@@ -2681,10 +2799,17 @@ Yxy             This uses a table 4 times larger (hence 4 times slower) than
 							depth <<= 1;
 						channel->lastHdepth = depth;
 					}
-					if (channel->playing) {
-						channel->playing->vibrato_speed = speed;
-						channel->playing->vibrato_depth = depth;
-						channel->playing->vibrato_n++;
+					for (i = -1; i < DUMB_IT_N_NNA_CHANNELS; i++) {
+						if (i < 0) playing = channel->playing;
+						else {
+							playing = sigrenderer->playing[i];
+							if (!playing || playing->channel != channel) continue;
+						}
+						if (playing) {
+							playing->vibrato_speed = speed;
+							playing->vibrato_depth = depth;
+							playing->vibrato_n++;
+						}
 					}
 				}
 				break;
@@ -3571,7 +3696,7 @@ static int it_envelope_end(IT_PLAYING *playing, IT_ENVELOPE *envelope, IT_PLAYIN
 /* Returns 1 when fading should be initiated for a volume envelope. */
 static int update_it_envelope(IT_PLAYING *playing, IT_ENVELOPE *envelope, IT_PLAYING_ENVELOPE *pe, int flags)
 {
-	if (!(playing->enabled_envelopes & flags))
+	if (!(playing->enabled_envelopes & flags) || !envelope->n_nodes)
 		return 0;
 
 	ASSERT(envelope->n_nodes > 0);
@@ -4287,13 +4412,13 @@ static float calculate_volume(DUMB_IT_SIGRENDERER *sigrenderer, IT_PLAYING *play
 			vol = (rand() % 129) - 64;
 			break;
 		case 4:
-			vol = it_xm_squarewave[playing->vibrato_time];
+			vol = it_xm_squarewave[playing->tremolo_time];
 			break;
 		case 5:
-			vol = it_xm_ramp[playing->vibrato_time];
+			vol = it_xm_ramp[playing->tremolo_time];
 			break;
 		case 6:
-			vol = it_xm_ramp[255-playing->vibrato_time];
+			vol = it_xm_ramp[255-((sigrenderer->sigdata->flags & IT_WAS_A_MOD)?playing->vibrato_time:playing->tremolo_time)];
 			break;
 		}
 		vol *= playing->tremolo_depth;
@@ -4314,7 +4439,7 @@ static float calculate_volume(DUMB_IT_SIGRENDERER *sigrenderer, IT_PLAYING *play
 		volume *= 1.0f / ((64 << 5) * 64.0f * 64.0f * 128.0f * 128.0f);
 
 		if (volume && playing->instrument) {
-			if (playing->enabled_envelopes & IT_ENV_VOLUME) {
+			if (playing->enabled_envelopes & IT_ENV_VOLUME && playing->env_instrument->volume_envelope.n_nodes) {
 				volume *= envelope_get_y(&playing->env_instrument->volume_envelope, &playing->volume_envelope);
 				volume *= 1.0f / (64 << IT_ENVELOPE_SHIFT);
 			}
diff --git a/dumb/src/it/readmod.c b/dumb/src/it/readmod.c
index 05c1ba86..6995ffc2 100644
--- a/dumb/src/it/readmod.c
+++ b/dumb/src/it/readmod.c
@@ -631,7 +631,7 @@ static DUMB_IT_SIGDATA *it_mod_load_sigdata(DUMBFILE *f, int rstrict)
 
 	/* Work out how many patterns there are. */
 	sigdata->n_patterns = -1;
-	for (i = 0; i < 128; i++)
+	for (i = 0; i < sigdata->n_orders; i++)
 		if (sigdata->n_patterns < sigdata->order[i])
 			sigdata->n_patterns = sigdata->order[i];
 	sigdata->n_patterns++;
diff --git a/dumb/src/it/readokt.c b/dumb/src/it/readokt.c
index 9ae05957..1f2fa944 100644
--- a/dumb/src/it/readokt.c
+++ b/dumb/src/it/readokt.c
@@ -497,7 +497,7 @@ static DUMB_IT_SIGDATA *it_okt_load_sigdata(DUMBFILE *f, int restrict)
 			j++;
 		}
 	}
-	for (; i < sigdata->n_samples; i++) {
+	for (; i < (unsigned)sigdata->n_samples; i++) {
 		sigdata->sample[i].flags = 0;
 	}
 
diff --git a/dumb/src/it/readstm.c b/dumb/src/it/readstm.c
index be1b1572..a4b00f79 100644
--- a/dumb/src/it/readstm.c
+++ b/dumb/src/it/readstm.c
@@ -354,7 +354,7 @@ static DUMB_IT_SIGDATA *it_stm_load_sigdata(DUMBFILE *f, int * version)
 
 	for ( n = 0, q = o / 16; n < sigdata->n_samples; ++n ) {
 		if ( sample_offset[ n ] ) {
-			sample_offset[ n ] -= q;
+			sample_offset[ n ] = (unsigned short)(sample_offset[ n ] - q);
 		}
 	}
 
diff --git a/dumb/src/it/readxm.c b/dumb/src/it/readxm.c
index 7d1b4657..1930ba93 100644
--- a/dumb/src/it/readxm.c
+++ b/dumb/src/it/readxm.c
@@ -111,6 +111,7 @@ typedef struct XM_INSTRUMENT_EXTRA
 	int vibrato_sweep; /* 0-0xFF */
 	int vibrato_depth; /* 0-0x0F */
 	int vibrato_speed; /* 0-0x3F */
+	int sample_header_size;
 }
 XM_INSTRUMENT_EXTRA;
 
@@ -359,19 +360,150 @@ static int it_xm_make_envelope(IT_ENVELOPE *envelope, const unsigned short *data
 
 
 
+typedef struct LIMITED_XM LIMITED_XM;
+
+struct LIMITED_XM
+{
+	unsigned char *buffered;
+	long ptr, limit, allocated;
+	DUMBFILE *remaining;
+};
+
+/* XXX */
+struct DUMBFILE
+{
+	DUMBFILE_SYSTEM *dfs;
+	void *file;
+	long pos;
+};
+
+static int limit_xm_resize(void *f, long n)
+{
+	DUMBFILE *df = f;
+	LIMITED_XM *lx = df->file;
+	if (lx->buffered || n) {
+		if (n > lx->allocated) {
+			unsigned char *buffered = realloc( lx->buffered, n );
+			if ( !buffered ) return -1;
+			lx->buffered = buffered;
+			memset( buffered + lx->allocated, 0, n - lx->allocated );
+			lx->allocated = n;
+		}
+		if ( dumbfile_getnc( lx->buffered, n, lx->remaining ) < n ) return -1;
+	} else if (!n) {
+		if ( lx->buffered ) free( lx->buffered );
+		lx->buffered = NULL;
+		lx->allocated = 0;
+	}
+	lx->limit = n;
+	lx->ptr = 0;
+	return 0;
+}
+
+static int limit_xm_skip_end(void *f, int32 n)
+{
+	DUMBFILE *df = f;
+	LIMITED_XM *lx = df->file;
+	return dumbfile_skip( lx->remaining, n );
+}
+
+static int limit_xm_skip(void *f, int32 n)
+{
+	LIMITED_XM *lx = f;
+	lx->ptr += n;
+	return 0;
+}
+
+
+
+static int limit_xm_getc(void *f)
+{
+	LIMITED_XM *lx = f;
+	if (lx->ptr >= lx->allocated) {
+		return 0;
+	}
+	return lx->buffered[lx->ptr++];
+}
+
+
+
+static long limit_xm_getnc(char *ptr, int32 n, void *f)
+{
+	LIMITED_XM *lx = f;
+	int left;
+	left = lx->allocated - lx->ptr;
+	if (n > left) {
+		if (left > 0) {
+			memcpy( ptr, lx->buffered + lx->ptr, left );
+			memset( ptr + left, 0, n - left );
+		} else {
+			memset( ptr, 0, n );
+		}
+	} else {
+		memcpy( ptr, lx->buffered + lx->ptr, n );
+	}
+	lx->ptr += n;
+	return n;
+}
+
+
+
+static void limit_xm_close(void *f)
+{
+	LIMITED_XM *lx = f;
+	if (lx->buffered) free(lx->buffered);
+	/* Do NOT close lx->remaining */
+	free(f);
+}
+
+
+
+DUMBFILE_SYSTEM limit_xm_dfs = {
+	NULL,
+	&limit_xm_skip,
+	&limit_xm_getc,
+	&limit_xm_getnc,
+	&limit_xm_close
+};
+
+static DUMBFILE *dumbfile_limit_xm(DUMBFILE *f)
+{
+	LIMITED_XM * lx = malloc(sizeof(*lx));
+	lx->remaining = f;
+	lx->buffered = NULL;
+	lx->ptr = 0;
+	lx->limit = 0;
+	lx->allocated = 0;
+	return dumbfile_open_ex( lx, &limit_xm_dfs );
+}
+
 static int it_xm_read_instrument(IT_INSTRUMENT *instrument, XM_INSTRUMENT_EXTRA *extra, DUMBFILE *f)
 {
 	uint32 size, bytes_read;
 	unsigned short vol_points[24];
 	unsigned short pan_points[24];
 	int i, type;
+	const unsigned long max_size = 4 + 22 + 1 + 2 + 4 + 96 + 48 + 48 + 1 * 14 + 2 + 2;
+	unsigned long skip_end = 0;
 
 	/* Header size. Tends to be more than the actual size of the structure.
 	 * So unread bytes must be skipped before reading the first sample
 	 * header.
 	 */
+
+	if ( limit_xm_resize( f, 4 ) < 0 ) return -1;
+
 	size = dumbfile_igetl(f);
 
+	if ( size == 0 ) size = max_size;
+	else if ( size > max_size )
+	{
+		skip_end = size - max_size;
+		size = max_size;
+	}
+
+	if ( limit_xm_resize( f, size - 4 ) < 0 ) return -1;
+
 	dumbfile_getnc(instrument->name, 22, f);
 	instrument->name[22] = 0;
 	instrument->filename[0] = 0;
@@ -385,12 +517,11 @@ static int it_xm_read_instrument(IT_INSTRUMENT *instrument, XM_INSTRUMENT_EXTRA
 
 	if (extra->n_samples) {
 		/* sample header size */
-		dumbfile_skip(f, 4); // XXX can't be trusted, as there are trackers that write the wrong value here
 		/*i = dumbfile_igetl(f);
-		if (i && i != 0x28) { // XXX some crap with 0 here
-			TRACE("XM error: unexpected sample header size\n");
-			return -1;
-		}*/
+		if (!i || i > 0x28) i = 0x28;*/
+		dumbfile_skip(f, 4);
+		i = 0x28;
+		extra->sample_header_size = i;
 
 		/* sample map */
 		for (i = 0; i < 96; i++) {
@@ -476,7 +607,10 @@ static int it_xm_read_instrument(IT_INSTRUMENT *instrument, XM_INSTRUMENT_EXTRA
 		for (i = 0; i < 96; i++)
 			instrument->map_sample[i] = 0;
 
-	if (dumbfile_skip(f, size - bytes_read))
+	if (size > bytes_read && dumbfile_skip(f, size - bytes_read))
+		return -1;
+
+	if (skip_end && limit_xm_skip_end(f, skip_end))
 		return -1;
 
 	instrument->new_note_action = NNA_NOTE_CUT;
@@ -924,16 +1058,24 @@ static DUMB_IT_SIGDATA *it_xm_load_sigdata(DUMBFILE *f, int * version)
 		for (i = 0; i < sigdata->n_instruments; i++) {
 			XM_INSTRUMENT_EXTRA extra;
 
-			if (it_xm_read_instrument(&sigdata->instrument[i], &extra, f) < 0) {
+			DUMBFILE * lf = dumbfile_limit_xm( f );
+			if ( !lf ) {
+				_dumb_it_unload_sigdata(sigdata);
+				return NULL;
+			}
+
+			if (it_xm_read_instrument(&sigdata->instrument[i], &extra, lf) < 0) {
 				// XXX
 				if ( ! i )
 				{
 					TRACE("XM error: instrument %d\n", i+1);
+					dumbfile_close( lf );
 					_dumb_it_unload_sigdata(sigdata);
 					return NULL;
 				}
 				else
 				{
+					dumbfile_close( lf );
 					sigdata->n_instruments = i;
 					break;
 				}
@@ -948,17 +1090,31 @@ static DUMB_IT_SIGDATA *it_xm_load_sigdata(DUMBFILE *f, int * version)
 
 				sigdata->sample = safe_realloc(sigdata->sample, sizeof(*sigdata->sample)*(total_samples+extra.n_samples));
 				if (!sigdata->sample) {
+					dumbfile_close( lf );
 					_dumb_it_unload_sigdata(sigdata);
 					return NULL;
 				}
 				for (j = total_samples; j < total_samples+extra.n_samples; j++)
 					sigdata->sample[j].data = NULL;
 
+				if ( limit_xm_resize( lf, 0 ) < 0 ) {
+					dumbfile_close( lf );
+					_dumb_it_unload_sigdata( sigdata );
+					return NULL;
+				}
+
 				/* read instrument's samples */
 				for (j = 0; j < extra.n_samples; j++) {
 					IT_SAMPLE *sample = &sigdata->sample[total_samples+j];
-					int b = it_xm_read_sample_header(sample, f);
+					int b;
+					if ( limit_xm_resize( lf, extra.sample_header_size ) < 0 ) {
+						dumbfile_close( lf );
+						_dumb_it_unload_sigdata( sigdata );
+						return NULL;
+					}
+					b = it_xm_read_sample_header(sample, lf);
 					if (b < 0) {
+						dumbfile_close( lf );
 						_dumb_it_unload_sigdata(sigdata);
 						return NULL;
 					}
@@ -975,12 +1131,15 @@ static DUMB_IT_SIGDATA *it_xm_load_sigdata(DUMBFILE *f, int * version)
 				}
 				for (j = 0; j < extra.n_samples; j++) {
 					if (it_xm_read_sample_data(&sigdata->sample[total_samples+j], roguebytes[j], f) != 0) {
+						dumbfile_close( lf );
 						_dumb_it_unload_sigdata(sigdata);
 						return NULL;
 					}
 				}
 				total_samples += extra.n_samples;
 			}
+
+			dumbfile_close( lf );
 		}
 
 		sigdata->n_samples = total_samples;
@@ -1012,8 +1171,16 @@ static DUMB_IT_SIGDATA *it_xm_load_sigdata(DUMBFILE *f, int * version)
 		for (i = 0; i < sigdata->n_instruments; i++) {
 			XM_INSTRUMENT_EXTRA extra;
 
-			if (it_xm_read_instrument(&sigdata->instrument[i], &extra, f) < 0) {
+			DUMBFILE * lf = dumbfile_limit_xm( f );
+			if ( !lf ) {
+				free(roguebytes);
+				_dumb_it_unload_sigdata(sigdata);
+				return NULL;
+			}
+
+			if (it_xm_read_instrument(&sigdata->instrument[i], &extra, lf) < 0) {
 				TRACE("XM error: instrument %d\n", i+1);
+				dumbfile_close(lf);
 				free(roguebytes);
 				_dumb_it_unload_sigdata(sigdata);
 				return NULL;
@@ -1026,6 +1193,7 @@ static DUMB_IT_SIGDATA *it_xm_load_sigdata(DUMBFILE *f, int * version)
 
 				sigdata->sample = safe_realloc(sigdata->sample, sizeof(*sigdata->sample)*(total_samples+extra.n_samples));
 				if (!sigdata->sample) {
+					dumbfile_close( lf );
 					free(roguebytes);
 					_dumb_it_unload_sigdata(sigdata);
 					return NULL;
@@ -1033,10 +1201,24 @@ static DUMB_IT_SIGDATA *it_xm_load_sigdata(DUMBFILE *f, int * version)
 				for (j = total_samples; j < total_samples+extra.n_samples; j++)
 					sigdata->sample[j].data = NULL;
 
+				if ( limit_xm_resize( lf, 0 ) < 0 ) {
+					dumbfile_close( lf );
+					free( roguebytes );
+					_dumb_it_unload_sigdata( sigdata );
+					return NULL;
+				}
+
 				/* read instrument's samples */
 				for (j = 0; j < extra.n_samples; j++) {
 					IT_SAMPLE *sample = &sigdata->sample[total_samples+j];
-					int b = it_xm_read_sample_header(sample, f);
+					int b;
+					if ( limit_xm_resize( lf, extra.sample_header_size ) < 0 ) {
+							dumbfile_close( lf );
+							free( roguebytes );
+							_dumb_it_unload_sigdata( sigdata );
+							return NULL;
+					}
+					b = it_xm_read_sample_header(sample, lf);
 					if (b < 0) {
 						free(roguebytes);
 						_dumb_it_unload_sigdata(sigdata);
@@ -1055,6 +1237,8 @@ static DUMB_IT_SIGDATA *it_xm_load_sigdata(DUMBFILE *f, int * version)
 				}
 				total_samples += extra.n_samples;
 			}
+
+			dumbfile_close( lf );
 		}
 
 		sigdata->n_samples = total_samples;
diff --git a/src/svnrevision.h b/src/svnrevision.h
index cea54423..0c9a1c08 100644
--- a/src/svnrevision.h
+++ b/src/svnrevision.h
@@ -3,5 +3,5 @@
 // This file was automatically generated by the
 // updaterevision tool. Do not edit by hand.
 
-#define ZD_SVN_REVISION_STRING "4090"
-#define ZD_SVN_REVISION_NUMBER 4090
+#define ZD_SVN_REVISION_STRING "4100"
+#define ZD_SVN_REVISION_NUMBER 4100