diff --git a/sources/user_problem.F90 b/sources/user_problem.F90
index f262e37..0f612cb 100644
--- a/sources/user_problem.F90
+++ b/sources/user_problem.F90
@@ -153,10 +153,10 @@ module user_problem
     call get_parameter("statistics_append", append)
     select case(trim(append))
     case ("on", "ON", "t", "T", "y", "Y", "true", "TRUE", "yes", "YES")
-      write(fname, "('magnetic_flux.dat')")
+      write(fname, "('magnetic-flux.dat')")
       inquire(file = fname, exist = flag)
     case default
-      write(fname, "('magnetic_flux_',i2.2,'.dat')") rcount
+      write(fname, "('magnetic-flux_',i2.2,'.dat')") rcount
       flag = .false.
     end select