diff --git a/optional-requirements.txt b/optional-requirements.txt
index 30326da9..dabb83a5 100644
--- a/optional-requirements.txt
+++ b/optional-requirements.txt
@@ -3,3 +3,4 @@ pysocks
 python-socks[asyncio]
 hachoir
 pillow
+isal
diff --git a/telethon/tl/core/gzippacked.py b/telethon/tl/core/gzippacked.py
index fb4094e4..b586a39e 100644
--- a/telethon/tl/core/gzippacked.py
+++ b/telethon/tl/core/gzippacked.py
@@ -1,4 +1,7 @@
-import gzip
+try:
+    from isal import igzip as gzip
+except ImportError:
+    import gzip
 import struct
 
 from .. import TLObject