diff --git a/physics/Radiation/mersenne_twister.f b/physics/Radiation/mersenne_twister.f
index bdd0da080..f9f9668f1 100644
--- a/physics/Radiation/mersenne_twister.f
+++ b/physics/Radiation/mersenne_twister.f
@@ -182,7 +182,7 @@ module mersenne_twister
         integer,parameter:: tmaskc=-272236544    !< tempering parameter
         integer,parameter:: mag01(0:1)=(/0,mata/)
         integer,parameter:: iseed=4357
-        integer,parameter:: nrest=n+6
+        integer,parameter:: nrest=n+4
 !  Defined types
         type random_stat                         !< Generator state 
           private