diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 18a9d68c09..531ab42629 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,9 @@
 March 22, 2008 (Changes by Graf Zahl)
+- Added more options to Light_ForceLightning: Setting the first arg to 0
+  will behave as before, setting it to 1 will create exactly one lighting
+  and setting it to 2 will terminate lightning for the current level
+  completely. And it will also work on maps that don't have lightning set
+  in MAPINFO now.
 - Added: Sector movement that causes deep water to change its height now
   will trigger associated sector actions and adjust the actor's water level.
 - Fixed: The serializer for side_t::part never read the texture information
diff --git a/src/g_shared/a_lightning.cpp b/src/g_shared/a_lightning.cpp
index 501429e81d..7bf5ad842d 100644
--- a/src/g_shared/a_lightning.cpp
+++ b/src/g_shared/a_lightning.cpp
@@ -14,6 +14,7 @@ IMPLEMENT_CLASS (DLightningThinker)
 DLightningThinker::DLightningThinker ()
 	: DThinker (STAT_LIGHTNING)
 {
+	Stopped = false;
 	LightningLightLevels = NULL;
 	LightningFlashCount = 0;
 	NextLightningFlash = ((pr_lightning()&15)+5)*35; // don't flash at level start
@@ -37,7 +38,7 @@ void DLightningThinker::Serialize (FArchive &arc)
 
 	Super::Serialize (arc);
 
-	arc << NextLightningFlash << LightningFlashCount;
+	arc << Stopped << NextLightningFlash << LightningFlashCount;
 
 	if (arc.IsLoading ())
 	{
@@ -63,6 +64,7 @@ void DLightningThinker::Tick ()
 	else
 	{
 		--NextLightningFlash;
+		if (Stopped) Destroy();
 	}
 }
 
@@ -166,9 +168,21 @@ void DLightningThinker::LightningFlash ()
 	}
 }
 
-void DLightningThinker::ForceLightning ()
+void DLightningThinker::ForceLightning (int mode)
 {
-	NextLightningFlash = 0;
+	switch (mode)
+	{
+	default:
+		NextLightningFlash = 0;
+		break;
+
+	case 1:
+		NextLightningFlash = 0;
+		// Fall through
+	case 2:
+		Stopped = true;
+		break;
+	}
 }
 
 static DLightningThinker *LocateLightning ()
@@ -186,20 +200,15 @@ void P_StartLightning ()
 	}
 }
 
-void P_StopLightning ()
+void P_ForceLightning (int mode)
 {
 	DLightningThinker *lightning = LocateLightning ();
+	if (lightning == NULL)
+	{
+		lightning = new DLightningThinker ();
+	}
 	if (lightning != NULL)
 	{
-		lightning->Destroy ();
-	}
-}
-
-void P_ForceLightning ()
-{
-	DLightningThinker *lightning = LocateLightning ();
-	if (lightning != NULL)
-	{
-		lightning->ForceLightning ();
+		lightning->ForceLightning (mode);
 	}
 }
diff --git a/src/g_shared/a_lightning.h b/src/g_shared/a_lightning.h
index ff72df5534..4e3a08ebeb 100644
--- a/src/g_shared/a_lightning.h
+++ b/src/g_shared/a_lightning.h
@@ -15,18 +15,19 @@ public:
 	~DLightningThinker ();
 	void Serialize (FArchive &arc);
 	void Tick ();
-	void ForceLightning ();
+	void ForceLightning (int mode);
+	void TerminateLightning();
 
 protected:
 	void LightningFlash ();
 
 	int NextLightningFlash;
 	int LightningFlashCount;
+	bool Stopped;
 	BYTE *LightningLightLevels;
 };
 
 void P_StartLightning ();
-void P_StopLightning ();
-void P_ForceLightning ();
+void P_ForceLightning (int mode);
 
 #endif //__A_LIGHTNING_H__
diff --git a/src/p_lnspec.cpp b/src/p_lnspec.cpp
index 2be3039335..9ebf4c332c 100644
--- a/src/p_lnspec.cpp
+++ b/src/p_lnspec.cpp
@@ -1666,9 +1666,9 @@ FUNC(LS_Elevator_LowerToNearest)
 }
 
 FUNC(LS_Light_ForceLightning)
-// Light_ForceLightning (tag)
+// Light_ForceLightning (mode)
 {
-	P_ForceLightning ();
+	P_ForceLightning (arg0);
 	return true;
 }
 
diff --git a/src/version.h b/src/version.h
index 6dd8175cea..77eb4b184c 100644
--- a/src/version.h
+++ b/src/version.h
@@ -75,7 +75,7 @@
 // SAVESIG should match SAVEVER.
 
 // MINSAVEVER is the minimum level snapshot version that can be loaded.
-#define MINSAVEVER 836
+#define MINSAVEVER 837
 
 #if SVN_REVISION_NUMBER < MINSAVEVER
 // Never write a savegame with a version lower than what we need