diff --git a/galpy/orbit_src/integratePlanarOrbit.py b/galpy/orbit_src/integratePlanarOrbit.py
index <HASH>..<HASH> 100644
--- a/galpy/orbit_src/integratePlanarOrbit.py
+++ b/galpy/orbit_src/integratePlanarOrbit.py
@@ -69,8 +69,13 @@ def integratePlanarOrbit_leapfrog(pot,yo,t,rtol=None,atol=None):
                              p._omegas,p._gamma])
         elif isinstance(p,potential.SteadyLogSpiralPotential):
             pot_type.append(3)
-            pot_args.extend([p._amp,p._tform,p._tsteady,p._A,p._alpha,p._m,
-                             p._omegas,p._gamma])
+            if p._tform is None:
+                pot_args.extend([p._amp,p._tform,p._tsteady,p._A,p._alpha,p._m,
+                                 p._omegas,p._gamma])
+            else:
+                pot_args.extend([p._amp,float('nan'), float('nan'),
+                                 p._A,p._alpha,p._m,
+                                 p._omegas,p._gamma])
     pot_type= nu.array(pot_type,dtype=nu.int32,order='C')
     pot_args= nu.array(pot_args,dtype=nu.float64,order='C')
correct handling of parameters when going to C for SteadyLogSpiral