diff --git a/src/p_lights.c b/src/p_lights.c
index 77d05dad3..95171155e 100644
--- a/src/p_lights.c
+++ b/src/p_lights.c
@@ -352,19 +352,17 @@ void P_FadeLightBySector(sector_t *sector, INT32 destvalue, INT32 speed, boolean
 	P_AddThinker(&ll->thinker); // add thinker
 
 	ll->sector = sector;
+	ll->sourcelevel = sector->lightlevel;
 	ll->destlevel = destvalue;
 
 	if (ticbased)
 	{
-		ll->ticbased = ticbased;
-		ll->timer = abs(speed);
-		ll->speed = FixedFloor(FixedDiv(destvalue - sector->lightlevel, ll->timer))/FRACUNIT;
-		if (!ll->speed)
-			ll->speed = (destvalue < sector->lightlevel) ? -1 : 1;
-		ll->interval = max(FixedFloor(FixedDiv(ll->timer, abs(destvalue - sector->lightlevel)))/FRACUNIT, 1);
+		ll->ticbased = true;
+		ll->timer = ll->speed = abs(speed); // use ll->speed for total duration
 	}
 	else
 	{
+		ll->ticbased = false;
 		ll->timer = -1;
 		ll->speed = abs(speed);
 	}
@@ -389,15 +387,17 @@ void T_LightFade(lightlevel_t *ll)
 	{
 		if (--ll->timer <= 0)
 		{
-			ll->sector->lightlevel = (INT16)ll->destlevel; // set to dest lightlevel
+			ll->sector->lightlevel = ll->destlevel; // set to dest lightlevel
 			P_RemoveLighting(ll->sector); // clear lightingdata, remove thinker
 		}
-		else if (!(ll->timer % ll->interval))
+		else
 		{
-			if (ll->speed < 0)
-				ll->sector->lightlevel = max(ll->sector->lightlevel + (INT16)ll->speed, (INT16)ll->destlevel);
-			else
-				ll->sector->lightlevel = min(ll->sector->lightlevel + (INT16)ll->speed, (INT16)ll->destlevel);
+			INT16 delta = abs(ll->destlevel - ll->sourcelevel);
+			fixed_t factor = min(FixedDiv(ll->speed - ll->timer, ll->speed), 1*FRACUNIT);
+			if (ll->destlevel < ll->sourcelevel)
+				ll->sector->lightlevel = max(min(ll->sector->lightlevel, ll->sourcelevel - (INT16)FixedMul(delta, factor)), ll->destlevel);
+			else if (ll->destlevel > ll->sourcelevel)
+				ll->sector->lightlevel = min(max(ll->sector->lightlevel, ll->sourcelevel + (INT16)FixedMul(delta, factor)), ll->destlevel);
 		}
 		return;
 	}
@@ -408,12 +408,12 @@ void T_LightFade(lightlevel_t *ll)
 		if (ll->sector->lightlevel + ll->speed >= ll->destlevel)
 		{
 			// stop changing light level
-			ll->sector->lightlevel = (INT16)ll->destlevel; // set to dest lightlevel
+			ll->sector->lightlevel = ll->destlevel; // set to dest lightlevel
 
 			P_RemoveLighting(ll->sector); // clear lightingdata, remove thinker
 		}
 		else
-			ll->sector->lightlevel = (INT16)(ll->sector->lightlevel + (INT16)ll->speed); // move lightlevel
+			ll->sector->lightlevel += ll->speed; // move lightlevel
 	}
 	else
 	{
@@ -421,11 +421,11 @@ void T_LightFade(lightlevel_t *ll)
 		if (ll->sector->lightlevel - ll->speed <= ll->destlevel)
 		{
 			// stop changing light level
-			ll->sector->lightlevel = (INT16)ll->destlevel; // set to dest lightlevel
+			ll->sector->lightlevel = ll->destlevel; // set to dest lightlevel
 
 			P_RemoveLighting(ll->sector); // clear lightingdata, remove thinker
 		}
 		else
-			ll->sector->lightlevel = (INT16)(ll->sector->lightlevel - (INT16)ll->speed); // move lightlevel
+			ll->sector->lightlevel -= ll->speed; // move lightlevel
 	}
 }
diff --git a/src/p_saveg.c b/src/p_saveg.c
index eefee072d..e9f07de4c 100644
--- a/src/p_saveg.c
+++ b/src/p_saveg.c
@@ -1537,11 +1537,11 @@ static void SaveLightlevelThinker(const thinker_t *th, const UINT8 type)
 	const lightlevel_t *ht = (const void *)th;
 	WRITEUINT8(save_p, type);
 	WRITEUINT32(save_p, SaveSector(ht->sector));
-	WRITEINT32(save_p, ht->destlevel);
-	WRITEINT32(save_p, ht->speed);
+	WRITEINT16(save_p, ht->sourcelevel);
+	WRITEINT16(save_p, ht->destlevel);
+	WRITEINT16(save_p, ht->speed);
 	WRITEUINT8(save_p, (UINT8)ht->ticbased);
 	WRITEINT32(save_p, ht->timer);
-	WRITEUINT32(save_p, ht->interval);
 }
 
 //
@@ -2513,11 +2513,11 @@ static inline void LoadLightlevelThinker(actionf_p1 thinker)
 	lightlevel_t *ht = Z_Malloc(sizeof (*ht), PU_LEVSPEC, NULL);
 	ht->thinker.function.acp1 = thinker;
 	ht->sector = LoadSector(READUINT32(save_p));
-	ht->destlevel = READINT32(save_p);
-	ht->speed = READINT32(save_p);
+	ht->sourcelevel = READINT16(save_p);
+	ht->destlevel = READINT16(save_p);
+	ht->speed = READINT16(save_p);
 	ht->ticbased = (boolean)READUINT8(save_p);
 	ht->timer = READINT32(save_p);
-	ht->interval = READUINT32(save_p);
 	if (ht->sector)
 		ht->sector->lightingdata = ht;
 	P_AddThinker(&ht->thinker);
diff --git a/src/p_spec.h b/src/p_spec.h
index 1e327c5f2..69087d6c4 100644
--- a/src/p_spec.h
+++ b/src/p_spec.h
@@ -136,13 +136,13 @@ typedef struct
 {
 	thinker_t thinker; ///< Thinker in use for the effect.
 	sector_t *sector;  ///< Sector where action is taking place.
-	INT32 destlevel;   ///< Light level we're fading to.
-	INT32 speed;       ///< Speed at which to change light level.
+	INT16 sourcelevel; ///< Light level we're fading from.
+	INT16 destlevel;   ///< Light level we're fading to.
+	INT16 speed;       ///< Speed at which to change light level. OR: Tic-based duration
 
 	// Tic-based behavior
 	boolean ticbased;  ///< Tic-based logic
-	INT32 timer;    ///< Tic-based timer
-	UINT32 interval;   ///< Interval to deduct light level
+	INT32 timer;       ///< Tic-based timer
 } lightlevel_t;
 
 #define GLOWSPEED 8