diff --git a/sc2/src/sc2code/planets/devices.c b/sc2/src/sc2code/planets/devices.c
index 428375266..8d37ab8cc 100644
--- a/sc2/src/sc2code/planets/devices.c
+++ b/sc2/src/sc2code/planets/devices.c
@@ -203,7 +203,7 @@ UseCaster (void)
 	}
 
 	if (LOBYTE (GLOBAL (CurrentActivity)) != IN_INTERPLANETARY
-			|| pSolarSysState != NULL)
+			|| pSolarSysState == NULL)
 		return FALSE;
 
 	if (pSolarSysState->pOrbitalDesc == &pSolarSysState->PlanetDesc[1]