diff --git a/vunit/vhdl/helpers/src/helpers_pkg.vhd b/vunit/vhdl/helpers/src/helpers_pkg.vhd
new file mode 100644
index 0000000000..9d1b475dc4
--- /dev/null
+++ b/vunit/vhdl/helpers/src/helpers_pkg.vhd
@@ -0,0 +1,22 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this file,
+-- You can obtain one at http://mozilla.org/MPL/2.0/.
+--
+-- Copyright (c) 2014-2020, Lars Asplund lars.anders.asplund@gmail.com
+
+package helpers_pkg is
+    function calc_width(data_width : positive) return natural;
+end package;
+
+package body helpers_pkg is
+    function calc_width(d : positive) return natural is
+      variable i : natural;
+      variable v : natural := d-1;
+    begin
+      while v > 0 loop
+        v := v/2;
+        i := i + 1;
+      end loop;
+      return i;
+    end;
+end package body;
diff --git a/vunit/vhdl/verification_components/src/avalon_stream_pkg.vhd b/vunit/vhdl/verification_components/src/avalon_stream_pkg.vhd
index 74a59cd6a2..402aa5c0b7 100644
--- a/vunit/vhdl/verification_components/src/avalon_stream_pkg.vhd
+++ b/vunit/vhdl/verification_components/src/avalon_stream_pkg.vhd
@@ -10,6 +10,7 @@ use ieee.std_logic_1164.all;
 use work.logger_pkg.all;
 use work.stream_master_pkg.all;
 use work.stream_slave_pkg.all;
+use work.helpers_pkg.all;
 context work.com_context;
 context work.data_types_context;
 
@@ -45,7 +46,6 @@ package avalon_stream_pkg is
                                        channel_length : natural := 0) return avalon_sink_t;
   impure function data_length(source : avalon_source_t) return natural;
   impure function data_length(source : avalon_sink_t) return natural;
-  function calc_empty_length(data_width : positive) return natural;
   impure function empty_length(source : avalon_source_t) return natural;
   impure function empty_length(source : avalon_sink_t) return natural;
   impure function channel_length(source : avalon_source_t) return natural;
@@ -147,27 +147,16 @@ package body avalon_stream_pkg is
     return source.p_data_length;
   end;
 
-  function calc_empty_length(data_width : positive) return natural is
-    variable v : natural;
-    variable i : natural;
-  begin
-    assert data_width mod 8 = 0;
-    v := data_width/8-1;
-    while v > 0 loop
-      v := v/2;
-      i := i + 1;
-    end loop;
-    return i;
-  end;
-
   impure function empty_length(source : avalon_source_t) return natural is
   begin
-    return calc_empty_length(source.p_data_length);
+    assert source.p_data_length mod 8 = 0;
+    return calc_width(source.p_data_length/8);
   end;
 
   impure function empty_length(source : avalon_sink_t) return natural is
   begin
-    return calc_empty_length(source.p_data_length);
+    assert source.p_data_length mod 8 = 0;
+    return calc_width(source.p_data_length/8);
   end;
 
   impure function channel_length(source : avalon_source_t) return natural is