diff --git a/m3u8/parser.py b/m3u8/parser.py
index 3f17d8a4..28b2e155 100644
--- a/m3u8/parser.py
+++ b/m3u8/parser.py
@@ -319,6 +319,9 @@ def _parse_attribute_list(prefix, line, attribute_parser, default_parser=None):
     params = ATTRIBUTELISTPATTERN.split(line.replace(prefix + ":", ""))[1::2]
 
     attributes = {}
+    if not line.startswith(prefix+':') :
+        return attributes
+
     for param in params:
         param_parts = param.split("=", 1)
         if len(param_parts) == 1:
diff --git a/tests/playlists.py b/tests/playlists.py
index 2e3063d0..14338a31 100755
--- a/tests/playlists.py
+++ b/tests/playlists.py
@@ -98,7 +98,19 @@
 http://media.example.com/fileSequence52-3.ts
 """
 
-PLAYLIST_WITH_SESSION_ENCRYPTED_SEGMENTS = """
+PLAYLIST_WITH_CUSTOM_MEDIA_HEADER = '''#EXTM3U
+#EXT-X-VERSION:3
+#EXT-X-TARGETDURATION:6
+#EXT-X-MEDIA-SEQUENCE:1
+#EXT-X-MEDIA-READY:7f659f6f09bce196d7
+#EXT-X-KEY:METHOD=AES-128,URI="[KEY]",IV=[IV]
+#EXTINF:6.0,
+https://cdn.example.com/vod/hash:XXX/file.mp4/media-1.ts
+#EXTINF:6.28,
+https://cdn.example.com/vod/hash:XXX/file.mp4/media-2.ts
+'''
+
+PLAYLIST_WITH_SESSION_ENCRYPTED_SEGMENTS = '''
 #EXTM3U
 #EXT-X-MEDIA-SEQUENCE:7794
 #EXT-X-TARGETDURATION:15
@@ -111,7 +123,7 @@
 http://media.example.com/fileSequence52-2.ts
 #EXTINF:15,
 http://media.example.com/fileSequence52-3.ts
-"""
+'''
 
 VARIANT_PLAYLIST = """
 #EXTM3U
diff --git a/tests/test_model.py b/tests/test_model.py
index 0789ad15..e87afab2 100755
--- a/tests/test_model.py
+++ b/tests/test_model.py
@@ -382,6 +382,10 @@ def test_session_key_attribute_without_initialization_vector():
     assert None is obj.session_keys[0].iv
 
 
+def test_parse_custom_media_header():
+    obj = m3u8.M3U8(playlists.PLAYLIST_WITH_CUSTOM_MEDIA_HEADER)
+
+
 def test_segments_attribute():
     obj = m3u8.M3U8(playlists.SIMPLE_PLAYLIST)
     mock_parser_data(