diff --git a/downloader/downloader/hls_playlist.py b/downloader/downloader/hls_playlist.py
index d737b01..7a764e9 100644
--- a/downloader/downloader/hls_playlist.py
+++ b/downloader/downloader/hls_playlist.py
@@ -62,7 +62,7 @@ IFrameStreamInfo = namedtuple("IFrameStreamInfo", "bandwidth program_id "
 Playlist = namedtuple("Playlist", "uri stream_info media is_iframe")
 Resolution = namedtuple("Resolution", "width height")
 Segment = namedtuple("Segment", "uri duration title key discontinuity "
-                                "byterange date map")
+                                "byterange date map scte35")
 
 
 class M3U8(object):
@@ -184,11 +184,12 @@ class M3U8Parser(object):
                 date = self.state.pop("date", None)
                 map_ = self.state.get("map")
                 key = self.state.get("key")
+                scte35 = self.state.get("scte35")
 
                 segment = Segment(self.uri(line), extinf[0],
                                   extinf[1], key,
                                   self.state.pop("discontinuity", False),
-                                  byterange, date, map_)
+                                  byterange, date, map_, scte35)
                 self.m3u8.segments.append(segment)
             elif self.state.pop("expect_playlist", None):
                 streaminf = self.state.pop("streaminf", {})
@@ -259,6 +260,13 @@ class M3U8Parser(object):
             start = Start(attr.get("TIME-OFFSET"),
                           self.parse_bool(attr.get("PRECISE", "NO")))
             self.m3u8.start = start
+        elif line.startswith("#EXT-X-SCTE35-OUT"):
+            # marks start of ad, with optional URL
+            attr = self.parse_tag(line, self.parse_attributes)
+            self.state["scte35"] = attr.get('URL') or "unknown"
+        elif line.startswith("#EXT-X-SCTE35-IN"):
+            # marks end of ad
+            self.state["scte35"] = None
 
     def parse(self, data):
         self.state = {}
diff --git a/downloader/downloader/main.py b/downloader/downloader/main.py
index 7fe473c..d0810af 100644
--- a/downloader/downloader/main.py
+++ b/downloader/downloader/main.py
@@ -79,8 +79,11 @@ class StreamsManager(object):
 	one, but during switchover there may be 2 - one old one continuing to (try to) operate while
 	the second one confirms it's working. While trying to get a url working, it won't retry, it'll
 	just ask the manager immediately to create yet another new worker then quit.
-	When one successfully fetches a playlist for the first time, it marks all older
-	workers as able to shut down by calling manager.mark_working().
+	When one successfully fetches a playlist for the first time, and confirms it has a non-ad
+	segment, it marks all older workers as able to shut down by calling manager.mark_working().
+	We wait for a non-ad segment because on first connect, a preroll ad may play.
+	We don't want to give up on the old connection (which may contain segments covering
+	the time the preroll ad is playing) until the ad is over.
 
 	Creation of a new stream worker may be triggered by:
 	* An existing worker failing to refresh its playlist
@@ -328,11 +331,17 @@ class StreamWorker(object):
 
 			# We successfully got the playlist at least once
 			first = False
-			self.manager.mark_working(self)
 
 			# Start any new segment getters
 			date = None # tracks date in case some segment doesn't include it
 			for segment in playlist.segments:
+				if segment.scte35:
+					self.logger.debug("Ignoring ad segment for {}".format(segment.scte35))
+					continue
+
+				# We've got our first non-ad segment, so we're good to take it from here.
+				self.manager.mark_working(self)
+
 				if segment.date:
 					date = dateutil.parser.parse(segment.date)
 				if segment.uri not in self.getters:
diff --git a/downloader/downloader/twitch.py b/downloader/downloader/twitch.py
index 5e7fcfe..94b60da 100644
--- a/downloader/downloader/twitch.py
+++ b/downloader/downloader/twitch.py
@@ -38,6 +38,9 @@ def get_master_playlist(channel, session=requests):
 			# Also observed in the wild but not used in streamlink:
 			# "playlist_include_framerate": "true"
 			# "reassignments_supported": "true"
+			# It's reported that setting this may affect whether you get ads, but this is
+			# in flux. Better to just blend in with the crowd for now.
+			# "platform": "_"
 		},
 	)
 	resp.raise_for_status() # getting master playlist