diff --git a/src/crater/module_crater.f90 b/src/crater/module_crater.f90
index 1f6860b1..b96fb0dd 100644
--- a/src/crater/module_crater.f90
+++ b/src/crater/module_crater.f90
@@ -267,6 +267,7 @@ function crater_degradation_function(user,r) result(Kd)
       use module_globals
       type(usertype),intent(in) :: user
       real(DP),intent(in) :: r
+      real(DP) :: Kd
       end function crater_degradation_function
    end interface