diff --git a/Source/ROLib/Modules/ModuleROTank_KorolevCross.cs b/Source/ROLib/Modules/ModuleROTank_KorolevCross.cs
index 6ea4b78..8b6327f 100644
--- a/Source/ROLib/Modules/ModuleROTank_KorolevCross.cs
+++ b/Source/ROLib/Modules/ModuleROTank_KorolevCross.cs
@@ -136,7 +136,7 @@ private void CreateJoint()
 
         public override void OnFixedUpdate()
         {
-            if (!isFinished && decoupler.isDecoupled)
+            if (!isFinished && decoupler != null && decoupler.isDecoupled)
             {
                 float mass = GetPartDryMassRecursive(part);