diff --git a/sources/io.F90 b/sources/io.F90
index 5e20609..e649001 100644
--- a/sources/io.F90
+++ b/sources/io.F90
@@ -188,7 +188,7 @@ module io
 
 ! compression type (0 for no compressions, 1 for deflate, 32015 for zstandard)
 !
-  integer           , save :: compression = 0
+  integer           , save :: compression = 0, hclevel = 3
 
 ! HDF5 property object identifier
 !
@@ -435,20 +435,20 @@ module io
 
 ! get compression_level
 !
-          call get_parameter("compression_level", clevel)
+          call get_parameter("compression_level", hclevel)
 
 ! initialize proper compressor
 !
           if (status == 0) then
             select case(compression)
             case(H5Z_ZSTANDARD)
-              if (clevel < 1 .or. clevel > 20) clevel = 3
-              cd_values(:) = clevel
+              if (hclevel < 1 .or. hclevel > 20) hclevel = 3
+              cd_values(:) = hclevel
               call h5pset_filter_f(pid, H5Z_ZSTANDARD, H5Z_FLAG_OPTIONAL_F,    &
                                    cd_nelmts, cd_values, status)
             case(H5Z_DEFLATE)
-              if (clevel < 1 .or. clevel  > 9) clevel = 6
-              call h5pset_deflate_f(pid, clevel, status)
+              if (hclevel < 1 .or. hclevel  > 9) hclevel = 6
+              call h5pset_deflate_f(pid, hclevel, status)
             case default
             end select
           end if
@@ -619,10 +619,10 @@ module io
       select case(compression)
       case(H5Z_ZSTANDARD)
         call print_parameter(verbose, "HDF5 compression" , "zstd"   )
-        call print_parameter(verbose, "compression level", clevel   )
+        call print_parameter(verbose, "compression level", hclevel  )
       case(H5Z_DEFLATE)
         call print_parameter(verbose, "HDF5 compression" , "deflate")
-        call print_parameter(verbose, "compression level", clevel   )
+        call print_parameter(verbose, "compression level", hclevel  )
       case default
         call print_parameter(verbose, "HDF5 compression" , "none"   )
       end select