diff --git a/src/Core/Entities/OOPlanetEntity.m b/src/Core/Entities/OOPlanetEntity.m
index 6e2d0f42..b5dd8439 100644
--- a/src/Core/Entities/OOPlanetEntity.m
+++ b/src/Core/Entities/OOPlanetEntity.m
@@ -70,7 +70,7 @@ MA 02110-1301, USA.
 }
 
 
-const double kMesosphere = 10.0 * ATMOSPHERE_DEPTH;	// atmosphere effect starts at 10x the height of the clouds
+static const double kMesosphere = 10.0 * ATMOSPHERE_DEPTH;	// atmosphere effect starts at 10x the height of the clouds
 
 
 - (id) initFromDictionary:(NSDictionary *)dict withAtmosphere:(BOOL)atmosphere andSeed:(Random_Seed)seed