diff --git a/bob/bio/base/script/figure.py b/bob/bio/base/script/figure.py
index aba8cecfd3cc599059369f155d57b30bc3d3b91a..887ac3e767013d15ddabe7f2d9ff1f96d88161ea 100644
--- a/bob/bio/base/script/figure.py
+++ b/bob/bio/base/script/figure.py
@@ -202,8 +202,8 @@ class Hist(measure_figure.Hist):
     def _setup_hist(self, neg, pos):
         self._title_base = 'Biometric scores'
         self._density_hist(
-            pos[0], label='Genuines', alpha=0.9, color='C2'
+            pos[0], n=0, label='Genuines', alpha=0.9, color='C2'
         )
         self._density_hist(
-            neg[0], label='Zero-effort impostors', alpha=0.8, color='C0'
+            neg[0], n=1, label='Zero-effort impostors', alpha=0.8, color='C0'
         )
diff --git a/bob/bio/base/test/test_commands.py b/bob/bio/base/test/test_commands.py
index 22f01ebe4c0901ed108a8a530ccf6d6f453e46fa..c834a52dfdd31e6e427dca0473c3dc432f16d5cb 100644
--- a/bob/bio/base/test/test_commands.py
+++ b/bob/bio/base/test/test_commands.py
@@ -191,14 +191,14 @@ def test_hist():
     with runner.isolated_filesystem():
         result = runner.invoke(commands.hist, ['--criterion', 'hter', '--output',
                                                'HISTO.pdf', '-b',
-                                               30,'--no-evaluation', dev1, dev2])
+                                               '30,auto','--no-evaluation', dev1, dev2])
         if result.output:
             click.echo(result.output)
         assert result.exit_code == 0, (result.exit_code, result.output)
 
     with runner.isolated_filesystem():
         result = runner.invoke(commands.hist, ['--criterion', 'eer', '--output',
-                                               'HISTO.pdf', '-b', 30,
+                                               'HISTO.pdf', '-b', '30',
                                                '-ts', 'A,B', dev1, test1, dev2,
                                                test2])
         if result.output: