diff --git a/README.md b/README.md
index 08da6ae..e82b5a9 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,8 @@ In addition, display alarms can be created or cleared.
 ```yaml
 my_calendar_name:
    ical_url: https://source-calendar.com/my_calendar.ics # Source calendar
+   request_headers: # (optional) add headers send when requesting the ical url 
+     - User-Agent: 'Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0'
    api_key: myapikey # (optional) append ?key=myapikey to your URL to grant access
    timezone: Europe/London # (optional) ensure all time comparisons are done in this TZ
    rules:
diff --git a/lib/ical_filter_proxy/calendar.rb b/lib/ical_filter_proxy/calendar.rb
index 1cba542..f9f4619 100644
--- a/lib/ical_filter_proxy/calendar.rb
+++ b/lib/ical_filter_proxy/calendar.rb
@@ -1,11 +1,12 @@
 module IcalFilterProxy
   class Calendar
-    attr_accessor :ical_url, :api_key, :timezone, :filter_rules, :clear_existing_alarms, :alarm_triggers
+    attr_accessor :ical_url, :api_key, :timezone, :filter_rules, :clear_existing_alarms, :alarm_triggers, :request_headers
 
-    def initialize(ical_url, api_key, timezone = 'UTC')
+    def initialize(ical_url, api_key, timezone = 'UTC', request_headers = {})
       self.ical_url = ical_url
       self.api_key = api_key
       self.timezone = timezone
+      self.request_headers = request_headers
 
       self.filter_rules = []
       self.clear_existing_alarms = false
@@ -58,7 +59,7 @@ def original_ics
     end
 
     def raw_original_ical
-      URI.open(ical_url).read
+      URI.open(ical_url, request_headers || {}).read
     end
   end
 end
diff --git a/lib/ical_filter_proxy/calendar_builder.rb b/lib/ical_filter_proxy/calendar_builder.rb
index 8d17260..da06054 100644
--- a/lib/ical_filter_proxy/calendar_builder.rb
+++ b/lib/ical_filter_proxy/calendar_builder.rb
@@ -20,7 +20,8 @@ def build
     def create_calendar
       @calendar = Calendar.new(calendar_config["ical_url"],
                                calendar_config["api_key"],
-                               calendar_config["timezone"])
+                               calendar_config["timezone"],
+                               calendar_config["request_headers"])
     end
 
     def add_rules