diff --git a/pattern_library/monkey_utils.py b/pattern_library/monkey_utils.py
index f00a192f..a030b220 100644
--- a/pattern_library/monkey_utils.py
+++ b/pattern_library/monkey_utils.py
@@ -25,6 +25,7 @@ def tag_func(parser, token):
 
         def node_render(context):
             if is_pattern_library_context(context):
+                tag_overridden = False
                 result = ''
 
                 # Load pattern's config
@@ -42,21 +43,23 @@ def node_render(context):
                     # Get config for specific arguments
                     tag_config = tag_config.get(arguments, {})
 
-                    # Return raw data (it can be string or a structure), if defined
+                    if 'raw' in tag_config:
+                        # Return raw data (it can be string or a structure), if defined
+                        result = tag_config['raw']
+                        tag_overridden = True
+                    elif 'template_name' in tag_config:
+                        # Render pattern, if raw string is not defined
+                        template_name = tag_config['template_name']
+                        request = context.get('request')
+                        result = render_pattern(request, template_name)
+                        tag_overridden = True
+
                     # TODO: Allow objects with the __str__ method
                     # In some cases we must return an object that can
                     # be rendered as a string `{{ result }}`
                     # and allow users to access it's attributes `{{ result.url }}`
-                    result = tag_config.get('raw')
-
-                    # Render pattern, if raw string is not defined
-                    if not result:
-                        template_name = tag_config.get('template_name')
-                        if template_name:
-                            request = context.get('request')
-                            result = render_pattern(request, template_name)
 
-                if result:
+                if tag_overridden:
                     if isinstance(original_node, SimpleNode):
                         # If it's a SimpleNode try to use it's target_var
                         target_var = original_node.target_var
diff --git a/runtests.py b/runtests.py
index a00f5866..376a46a5 100755
--- a/runtests.py
+++ b/runtests.py
@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+import argparse
 import os
 import sys
 
@@ -8,15 +9,32 @@
 
 import coverage
 
+parser = argparse.ArgumentParser()
+parser.add_argument(
+    '-v', '--verbosity', action='store', dest='verbosity', default=1,
+    type=int, choices=range(4),
+    help="Verbosity level; 0=minimal output, 1=normal output, 2=verbose output, 3=very verbose output",
+)
+
 if __name__ == "__main__":
+    # Coverage setup
     cov = coverage.Coverage()
     cov.start()
+
+    # Django setup
     os.environ['DJANGO_SETTINGS_MODULE'] = 'tests.test_settings'
     django.setup()
+
+    # Test runner setup
     TestRunner = get_runner(settings)
-    test_runner = TestRunner()
+    TestRunner.add_arguments(parser)
+    args = parser.parse_args()
+    test_runner = TestRunner(**vars(args))
     failures = test_runner.run_tests(["tests"])
+
+    # Generate coverage report
     cov.stop()
     cov.save()
     cov.html_report()
+
     sys.exit(bool(failures))
diff --git a/tests/templates/patterns/atoms/tags_test_atom/tags_test_atom.html b/tests/templates/patterns/atoms/tags_test_atom/tags_test_atom.html
new file mode 100644
index 00000000..09258c7d
--- /dev/null
+++ b/tests/templates/patterns/atoms/tags_test_atom/tags_test_atom.html
@@ -0,0 +1,5 @@
+{% load test_tags %}
+
+SAND{% error_tag empty_string %}WICH
+SAND{% error_tag none %}WICH
+SAND{% error_tag zero %}WICH
diff --git a/tests/templates/patterns/atoms/tags_test_atom/tags_test_atom.yaml b/tests/templates/patterns/atoms/tags_test_atom/tags_test_atom.yaml
new file mode 100644
index 00000000..0fe3edf6
--- /dev/null
+++ b/tests/templates/patterns/atoms/tags_test_atom/tags_test_atom.yaml
@@ -0,0 +1,8 @@
+tags:
+  error_tag:
+    empty_string:
+      raw: ''
+    none:
+      raw: null
+    zero:
+      raw: 0
diff --git a/tests/templatetags/__init__.py b/tests/templatetags/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/templatetags/test_tags.py b/tests/templatetags/test_tags.py
new file mode 100644
index 00000000..581edb9d
--- /dev/null
+++ b/tests/templatetags/test_tags.py
@@ -0,0 +1,14 @@
+from django import template
+
+from pattern_library.monkey_utils import override_tag
+
+register = template.Library()
+
+
+@register.simple_tag
+def error_tag(arg=None):
+    "Just raise an exception, never do anything"
+    raise Exception("error_tag raised an exception")
+
+
+override_tag(register, 'error_tag')
diff --git a/tests/tests/test_tags.py b/tests/tests/test_tags.py
index a525f061..efee2592 100644
--- a/tests/tests/test_tags.py
+++ b/tests/tests/test_tags.py
@@ -1,5 +1,13 @@
+from django.core.urlresolvers import reverse
 from django.test import SimpleTestCase
 
 
 class TagsTesCase(SimpleTestCase):
-    pass
+    def test_falsey_raw_values_for_tag_output(self):
+        response = self.client.get(reverse(
+            'pattern_library:display_pattern',
+            kwargs={'template_name': 'patterns/atoms/tags_test_atom/tags_test_atom.html'},
+        ))
+        self.assertContains(response, "SANDWICH")
+        self.assertContains(response, "SANDNoneWICH")
+        self.assertContains(response, "SAND0WICH")