diff --git a/src/pretix/base/models/event.py b/src/pretix/base/models/event.py
index 9ab807b79..54bc7179f 100644
--- a/src/pretix/base/models/event.py
+++ b/src/pretix/base/models/event.py
@@ -199,8 +199,8 @@ class Event(EventMixin, LoggedModel):
     slug = models.SlugField(
         max_length=50, db_index=True,
         help_text=_(
-            "Should be short, only contain lowercase letters and numbers, and must be unique among your events. "
-            "We recommend some kind of abbreviation or a date with less than 10 characters that can be easily "
+            "Should be short, only contain lowercase letters, numbers, dots, and dashes, and must be unique among your "
+            "events. We recommend some kind of abbreviation or a date with less than 10 characters that can be easily "
             "remembered, but you can also choose to use a random value. "
             "This will be used in URLs, order codes, invoice numbers, and bank transfer references."),
         validators=[
diff --git a/src/pretix/base/models/organizer.py b/src/pretix/base/models/organizer.py
index b7e5beba8..6ad4b0008 100644
--- a/src/pretix/base/models/organizer.py
+++ b/src/pretix/base/models/organizer.py
@@ -32,8 +32,9 @@ class Organizer(LoggedModel):
     slug = models.SlugField(
         max_length=50, db_index=True,
         help_text=_(
-            "Should be short, only contain lowercase letters and numbers, and must be unique among your events. "
-            "This is being used in addresses and bank transfer references."),
+            "Should be short, only contain lowercase letters, numbers, dots, and dashes, and must be unique among your "
+            "events. "
+            "This is being used in URLs to refer to your events."),
         validators=[
             RegexValidator(
                 regex="^[a-zA-Z0-9.-]+$",