diff --git a/bob/bio/base/test/test_config_file.py b/bob/bio/base/test/test_config_file.py
index 39e6c347ccd2d97edf48e6bcf57a771f1ee25d40..5c851fc0f8e5b916e414530edca7abc48b9db187 100644
--- a/bob/bio/base/test/test_config_file.py
+++ b/bob/bio/base/test/test_config_file.py
@@ -76,7 +76,7 @@ def test_basic():
       'result_directory = "%s"' % test_dir,
       ])
 
-    args = parse_arguments(['-c', test_config_file.name])
+    args = parse_arguments([test_config_file.name])
 
     assert args.zt_norm is True
     assert args.verbose == 1
@@ -117,7 +117,7 @@ def test_compare_to_cmdline_basic():
       'result_directory = "%s"' % test_dir,
       ])
 
-    args_file = parse_arguments(['-c', test_config_file.name])
+    args_file = parse_arguments([test_config_file.name])
 
     # now do the same with command-line arguments, ensure result is equal
     args_cmdline = parse_arguments([
@@ -159,7 +159,7 @@ def test_compare_to_cmdline_resources():
       'preferred_package = "bob.bio.base"',
       ])
 
-    args_file = parse_arguments(['-c', test_config_file.name])
+    args_file = parse_arguments([test_config_file.name])
 
     # now do the same with command-line arguments, ensure result is equal
     args_cmdline = parse_arguments([
@@ -204,7 +204,7 @@ def test_compare_to_cmdline_skip():
       'preferred_package = "bob.bio.base"',
       ])
 
-    args_file = parse_arguments(['-c', test_config_file.name])
+    args_file = parse_arguments([test_config_file.name])
 
     # now do the same with command-line arguments, ensure result is equal
     args_cmdline = parse_arguments([
diff --git a/bob/bio/base/tools/command_line.py b/bob/bio/base/tools/command_line.py
index ba4379960571bdf35e23f117b5c34c3e0e94a56d..f88e8011c7ac6a6b76f69bd4df5416867c4b321f 100644
--- a/bob/bio/base/tools/command_line.py
+++ b/bob/bio/base/tools/command_line.py
@@ -47,8 +47,7 @@ def command_line_parser(description=__doc__, exclude_resources_from=[]):
   #######################################################################################
   ############## options that are required to be specified #######################
   config_group = parser.add_argument_group('\nParameters defining the experiment. Most of these parameters can be a registered resource, a configuration file, or even a string that defines a newly created object')
-  config_group.add_argument('-c', '--configuration-file',
-      help = 'A configuration file containing one or more of "database", "preprocessor", "extractor", "algorithm" and/or "grid"')
+  config_group.add_argument('configuration_file', metavar='PATH', nargs='?', help = 'A configuration file containing one or more of "database", "preprocessor", "extractor", "algorithm" and/or "grid"')
   config_group.add_argument('-d', '--database', metavar = 'x', nargs = '+',
       help = 'Database and the protocol; registered databases are: %s' % utils.resource_keys('database', exclude_resources_from))
   config_group.add_argument('-p', '--preprocessor', metavar = 'x', nargs = '+',
@@ -169,7 +168,7 @@ def _take_from_config_or_command_line(args, config, keyword, default, required=T
     setattr(args, keyword, val)
 
   elif required:
-    raise ValueError("Please specify a %s either on command line (via --%s) or in the configuration file (via --configuration-file)" %(keyword, keyword))
+    raise ValueError("Please specify a %s either on command line (via --%s) or in a configuration file" %(keyword, keyword))
 
 
 def initialize(parsers, command_line_parameters = None, skips = []):