diff --git a/src/gray_core.f90 b/src/gray_core.f90
index a3d0880..7103f14 100644
--- a/src/gray_core.f90
+++ b/src/gray_core.f90
@@ -82,8 +82,6 @@ contains
     logical,       dimension(:), pointer :: iwait=>null()
     logical,       dimension(:,:), pointer :: iroff=>null()
 
-    ! parameters log in file headers
-    character(len=headw), dimension(headl) :: strheader
     ! buffer for formatting log messages
     character(256) :: msg
 
@@ -131,8 +129,7 @@ contains
     ! ========= set environment END =========
 
     ! ======== pre-proc prints BEGIN ========
-    call print_parameters(params, strheader)
-    call print_headers(strheader)
+    call print_headers(params)
 
     ! print ψ surface for q=1.5 and q=2 on file and log psi,rhot,rhop
     call print_surfq([1.5_wp_, 2.0_wp_])
@@ -1890,21 +1887,23 @@ bb: do
 
 
 
-  subroutine print_headers(strheader)
+  subroutine print_headers(params)
     ! Prints the headers of all gray_main output tables
 
-    use units, only : uprj0, uwbm, udisp, ucenr, uoutr, upec, usumm, &
-                      unit_active
+    use units,       only : uprj0, uwbm, udisp, ucenr, uoutr, upec, usumm, &
+                            unit_active, active_units
+    use gray_params, only : gray_parameters, headw, headl, print_parameters
 
     implicit none
 
     ! subroutine arguments
-    character(len=*), dimension(:), intent(in) :: strheader
+    type(gray_parameters), intent(in) :: params
 
     ! local variables
     integer :: i, j
     integer        :: main_units(8)
     character(256) :: main_headers(8)
+    character(len=headw), dimension(headl) :: header
 
     main_units = [uprj0, uprj0+1, uwbm, udisp, ucenr, uoutr, upec, usumm]
 
@@ -1922,10 +1921,14 @@ bb: do
                       // 'chipol index_rt Jphimx dPdVmx drhotj drhotp P0 ' &
                       // 'cplO cplX'
 
+    if (all(active_units == 0)) return
+
+    call print_parameters(params, header)
+
     do i=1,size(main_units)
       if (unit_active(main_units(i))) then
-        do j=1,size(strheader)
-          write (main_units(i), '(1x,a)') strheader(j)
+        do j=1,size(header)
+          write (main_units(i), '(1x,a)') header(j)
         end do
         write (main_units(i), '(1x,a)') trim(main_headers(i))
       end if
diff --git a/src/main.f90 b/src/main.f90
index 50b97bf..65829be 100644
--- a/src/main.f90
+++ b/src/main.f90
@@ -443,12 +443,7 @@ contains
     ! ======= set environment  END  ======
 
     ! ======== pre-proc prints BEGIN ========
-    block
-      ! Parameters log in file headers
-      character(len=headw), dimension(headl) :: strheader
-      call print_parameters(params, strheader)
-      call print_headers(strheader)
-    end block
+    call print_headers(params)
 
     ! Print ψ surface for q=1.5 and q=2 on file and psi,rhot,rhop on stdout
     call print_surfq([1.5_wp_, 2.0_wp_])