diff --git a/sc2/src/sc2code/planets/gencol.c b/sc2/src/sc2code/planets/gencol.c
index 9d4b388fe..bad0e46b3 100644
--- a/sc2/src/sc2code/planets/gencol.c
+++ b/sc2/src/sc2code/planets/gencol.c
@@ -82,7 +82,7 @@ GenerateColony (BYTE control)
 			PPLANET_DESC pMinPlanet;
 
 			pMinPlanet = &pSolarSysState->PlanetDesc[0];
-			FillOrbits ((BYTE)~0, pMinPlanet, FALSE);
+			FillOrbits (pSolarSysState, (BYTE)~0, pMinPlanet, FALSE);
 
 			pMinPlanet->radius = EARTH_RADIUS * 115L / 100;
 			angle = ARCTAN (pMinPlanet->location.x, pMinPlanet->location.y);
diff --git a/sc2/src/sc2code/planets/genshof.c b/sc2/src/sc2code/planets/genshof.c
index 81e11f4d0..6e37dd3e4 100644
--- a/sc2/src/sc2code/planets/genshof.c
+++ b/sc2/src/sc2code/planets/genshof.c
@@ -130,7 +130,8 @@ GenerateShofixti (BYTE control)
 					pCurDesc->data_index = METAL_WORLD;
 			}
 
-			FillOrbits (NUM_PLANETS, &pSolarSysState->PlanetDesc[0], TRUE);
+			FillOrbits (pSolarSysState,
+					NUM_PLANETS, &pSolarSysState->PlanetDesc[0], TRUE);
 			break;
 		}
 		default:
diff --git a/sc2/src/sc2code/planets/genspa.c b/sc2/src/sc2code/planets/genspa.c
index 21924cbe0..516891f8a 100644
--- a/sc2/src/sc2code/planets/genspa.c
+++ b/sc2/src/sc2code/planets/genspa.c
@@ -94,7 +94,9 @@ GenerateSpathi (BYTE control)
 			PPLANET_DESC pMinPlanet;
 
 			pMinPlanet = &pSolarSysState->PlanetDesc[0];
-			FillOrbits (pSolarSysState->SunDesc[0].NumPlanets = 1, pMinPlanet, FALSE);
+			FillOrbits (pSolarSysState,
+					pSolarSysState->SunDesc[0].NumPlanets = 1, pMinPlanet,
+					FALSE);
 
 			pMinPlanet->radius = EARTH_RADIUS * 1150L / 100;
 			angle = ARCTAN (pMinPlanet->location.x, pMinPlanet->location.y);
diff --git a/sc2/src/sc2code/planets/orbits.c b/sc2/src/sc2code/planets/orbits.c
index 8ad9f2dac..ee6d7c6bb 100644
--- a/sc2/src/sc2code/planets/orbits.c
+++ b/sc2/src/sc2code/planets/orbits.c
@@ -469,8 +469,8 @@ YellowDistribution (BYTE which_world)
 #define SUPERGIANT_GASG_DIST SCALE_RADIUS (33)
 
 void
-FillOrbits (BYTE NumPlanets, PPLANET_DESC pBaseDesc, BOOLEAN
-		TypesDefined)
+FillOrbits (PSOLARSYS_STATE system,
+		BYTE NumPlanets, PPLANET_DESC pBaseDesc, BOOLEAN TypesDefined)
 { /* Generate Planets in orbit around star */
 	BYTE StarColor, PlanetCount, MaxPlanet;
 	BOOLEAN GeneratingMoons;
@@ -492,7 +492,7 @@ char scolor[] = {'B', 'G', 'O', 'R', 'W', 'Y'};
 #endif /* DEBUG_ORBITS */
 
 	pPD = pBaseDesc;
-	StarSize = pSolarSysState->SunDesc[0].data_index;
+	StarSize = system->SunDesc[0].data_index;
 	StarColor = STAR_COLOR (CurStarDescPtr->Type);
 
 	if (NumPlanets == (BYTE)~0)
@@ -501,7 +501,7 @@ char scolor[] = {'B', 'G', 'O', 'R', 'W', 'Y'};
 		while ((NumPlanets = (BYTE)(LOWORD (TFB_Random())
 				% MAX_GENERATED_PLANETS)) == 0)
 			;
-		pSolarSysState->SunDesc[0].NumPlanets = NumPlanets;
+		system->SunDesc[0].NumPlanets = NumPlanets;
 	}
 
 #ifdef DEBUG_ORBITS
@@ -510,7 +510,7 @@ char scolor[] = {'B', 'G', 'O', 'R', 'W', 'Y'};
 			scolor[STAR_COLOR (CurStarDescPtr->Type)],
 			stype[STAR_TYPE (CurStarDescPtr->Type)]);
 #endif /* DEBUG_ORBITS */
-	GeneratingMoons = (BOOLEAN) (pBaseDesc == pSolarSysState->MoonDesc);
+	GeneratingMoons = (BOOLEAN) (pBaseDesc == system->MoonDesc);
 	if (GeneratingMoons)
 		MaxPlanet = FIRST_LARGE_ROCKY_WORLD;
 	else
diff --git a/sc2/src/sc2code/planets/planets.h b/sc2/src/sc2code/planets/planets.h
index 841827d10..56ce16d97 100644
--- a/sc2/src/sc2code/planets/planets.h
+++ b/sc2/src/sc2code/planets/planets.h
@@ -203,8 +203,8 @@ extern void DrawSystem (SIZE radius, BOOLEAN IsInnerSystem);
 extern void DrawOval (PRECT pRect, BYTE num_off_pixels);
 extern void DrawFilledOval (PRECT pRect);
 extern void DoMissions (void);
-extern void FillOrbits (BYTE NumPlanets, PPLANET_DESC pBaseDesc, BOOLEAN
-		TypesDefined);
+extern void FillOrbits (PSOLARSYS_STATE system,
+		BYTE NumPlanets, PPLANET_DESC pBaseDesc, BOOLEAN TypesDefined);
 extern void ScanSystem (void);
 extern void ChangeSolarSys (void);
 extern BOOLEAN DoFlagshipCommands (PMENU_STATE pMS);
diff --git a/sc2/src/sc2code/planets/solarsys.c b/sc2/src/sc2code/planets/solarsys.c
index b73630858..f17b707a5 100644
--- a/sc2/src/sc2code/planets/solarsys.c
+++ b/sc2/src/sc2code/planets/solarsys.c
@@ -62,15 +62,15 @@ static SIZE old_radius;
 BYTE draw_sys_flags = DRAW_STARS | DRAW_PLANETS | DRAW_ORBITS
 		| DRAW_HYPER_COORDS | GRAB_BKGND;
 
+// NB. This function modifies the RNG state.
 static void
-GeneratePlanets (void)
+GeneratePlanets (PSOLARSYS_STATE system)
 {
 	COUNT i;
-	PPLANET_DESC pCurDesc;
+	PPLANET_DESC planet;
 
-	for (i = pSolarSysState->SunDesc[0].NumPlanets,
-			pCurDesc = &pSolarSysState->PlanetDesc[0]; i;
-			--i, ++pCurDesc)
+	for (i = system->SunDesc[0].NumPlanets,
+			planet = &system->PlanetDesc[0]; i; --i, ++planet)
 	{
 		DWORD rand_val;
 		BYTE byte_val;
@@ -81,7 +81,7 @@ GeneratePlanets (void)
 		byte_val = LOBYTE (rand_val);
 
 		num_moons = 0;
-		type = PlanData[pCurDesc->data_index & ~PLANET_SHIELDED].Type;
+		type = PlanData[planet->data_index & ~PLANET_SHIELDED].Type;
 		switch (PLANSIZE (type))
 		{
 			case LARGE_ROCKY_WORLD:
@@ -109,7 +109,7 @@ GeneratePlanets (void)
 				}
 				break;
 		}
-		pCurDesc->NumPlanets = num_moons;
+		planet->NumPlanets = num_moons;
 	}
 }
 
@@ -1638,13 +1638,15 @@ GenerateRandomIP (BYTE control)
 			break;
 		}
 		case GENERATE_MOONS:
-			FillOrbits (pSolarSysState->pBaseDesc->NumPlanets,
+			FillOrbits (pSolarSysState,
+					pSolarSysState->pBaseDesc->NumPlanets,
 					&pSolarSysState->MoonDesc[0], FALSE);
 			break;
 		case GENERATE_PLANETS:
 		{
-			FillOrbits ((BYTE)~0, &pSolarSysState->PlanetDesc[0], FALSE);
-			GeneratePlanets();
+			FillOrbits (pSolarSysState,
+					(BYTE)~0, &pSolarSysState->PlanetDesc[0], FALSE);
+			GeneratePlanets (pSolarSysState);
 			break;
 		}
 	}
diff --git a/sc2/src/sc2code/planets/surface.c b/sc2/src/sc2code/planets/surface.c
index 785f17efd..453449c60 100644
--- a/sc2/src/sc2code/planets/surface.c
+++ b/sc2/src/sc2code/planets/surface.c
@@ -254,7 +254,8 @@ GenerateLifeForms (SYSTEM_INFOPTR SysInfoPtr, PCOUNT pwhich_life)
 {
 	DWORD old_rand;
 
-	old_rand = TFB_SeedRandom (SysInfoPtr->PlanetInfo.ScanSeed[BIOLOGICAL_SCAN]);
+	old_rand = TFB_SeedRandom (
+			SysInfoPtr->PlanetInfo.ScanSeed[BIOLOGICAL_SCAN]);
 	*pwhich_life = CalcLifeForms (SysInfoPtr, *pwhich_life);
 	return (TFB_SeedRandom (old_rand));
 }