diff --git a/code/plastic_isotropic.f90 b/code/plastic_isotropic.f90
index 563952122..81d3055cf 100644
--- a/code/plastic_isotropic.f90
+++ b/code/plastic_isotropic.f90
@@ -50,10 +50,10 @@ module plastic_isotropic
      a, &
      aTolFlowstress, &
      aTolShear     , &
-     tausat_SinhFitA, &
-     tausat_SinhFitB, &
-     tausat_SinhFitC, &
-     tausat_SinhFitD
+     tausat_SinhFitA=0.0_pReal, &
+     tausat_SinhFitB=0.0_pReal, &
+     tausat_SinhFitC=0.0_pReal, &
+     tausat_SinhFitD=0.0_pReal
   logical :: &
      dilatation = .false.
  end type