diff --git a/event/models.py b/event/models.py
index 87a38d1..d7d8ba9 100644
--- a/event/models.py
+++ b/event/models.py
@@ -71,7 +71,10 @@ class ActivityTag(models.Model):
                     max_length=200,
                 )
     is_public = models.BooleanField(
-                    help_text=_("TODO"),
+                    help_text=_("Sert à faire une distinction dans"
+                                " l'affichage selon que cela soit"
+                                " destiné au public ou à l'équipe"
+                                " organisatrice"),
                 )
     color_regex = RegexValidator(
                 regex=r'^#(?:[0-9a-fA-F]{3}){1,2}$',
diff --git a/event/tests.py b/event/tests.py
index 4db30c8..813aa3b 100644
--- a/event/tests.py
+++ b/event/tests.py
@@ -1,4 +1,6 @@
 from django.contrib.auth.models import User
+from django.core.exceptions import ValidationError
+from django.db.utils import DataError
 from django.test import TestCase
 from datetime import timedelta
 from django.utils import timezone
@@ -123,3 +125,39 @@ class ActivityInheritanceTest(TestCase):
                 self.real_act.get_herited('tags').get().name,
                 "bar"
             )
+
+
+class ActivityTagColorTest(TestCase):
+    def test_positive_color_long(self):
+        self.tag = ActivityTag.objects.create(
+                        name="bar",
+                        is_public=True,
+                        color="#0F0F0F",
+                    )
+        self.tag.full_clean()
+
+    def test_positive_color_small(self):
+        self.tag = ActivityTag.objects.create(
+                        name="bar",
+                        is_public=True,
+                        color="#0F0",
+                    )
+        self.tag.full_clean()
+
+    def test_negative_color_1(self):
+        self.tag = ActivityTag.objects.create(
+                        name="bar",
+                        is_public=True,
+                        color="#ABCDEG",
+                    )
+        with self.assertRaises(ValidationError):
+            self.tag.full_clean()
+
+    def test_negative_color_2(self):
+        self.tag = ActivityTag.objects.create(
+                        name="bar",
+                        is_public=True,
+                        color="#ACDE-1",
+                    )
+        with self.assertRaises(ValidationError):
+            self.tag.full_clean()