diff --git a/copyparty/svchub.py b/copyparty/svchub.py
index d8769957..c2b192cf 100644
--- a/copyparty/svchub.py
+++ b/copyparty/svchub.py
@@ -14,7 +14,7 @@ from .util import mp
 from .authsrv import AuthSrv
 from .tcpsrv import TcpSrv
 from .up2k import Up2k
-from .th_srv import ThumbSrv, HAVE_PIL
+from .th_srv import ThumbSrv, HAVE_PIL, HAVE_WEBP
 
 
 class SvcHub(object):
@@ -47,6 +47,11 @@ class SvcHub(object):
         self.thumbsrv = None
         if not args.no_thumb:
             if HAVE_PIL:
+                if not HAVE_WEBP:
+                    args.th_no_webp = True
+                    msg = "setting --th-no-webp because either libwebp is not available or your Pillow is too old"
+                    self.log("thumb", msg, c=3)
+
                 self.thumbsrv = ThumbSrv(self, auth.vfs.all_vols)
             else:
                 msg = "need Pillow to create thumbnails; for example:\n  {} -m pip install --user Pillow"
diff --git a/copyparty/th_cli.py b/copyparty/th_cli.py
index 1e49a84a..bf26964e 100644
--- a/copyparty/th_cli.py
+++ b/copyparty/th_cli.py
@@ -21,12 +21,12 @@ class ThumbCli(object):
         if self.args.no_vthumb and ext in FMT_FF:
             return None
 
-        if fmt == "w" and self.args.th_no_webp:
-            fmt = "j"
-
         if fmt == "j" and self.args.th_no_jpg:
             fmt = "w"
 
+        if fmt == "w" and self.args.th_no_webp:
+            fmt = "j"
+
         tpath = thumb_path(ptop, rem, mtime, fmt)
         ret = None
         try:
diff --git a/copyparty/th_srv.py b/copyparty/th_srv.py
index 7d6163f8..f918787a 100644
--- a/copyparty/th_srv.py
+++ b/copyparty/th_srv.py
@@ -8,14 +8,13 @@ import threading
 import subprocess as sp
 
 from .__init__ import PY2
-from .util import fsenc, Queue, Cooldown
+from .util import fsenc, Queue, Cooldown, BytesIO
 from .mtag import HAVE_FFMPEG, HAVE_FFPROBE, ffprobe
 
 
 if not PY2:
     unicode = str
 
-
 try:
     HAVE_PIL = True
     from PIL import Image, ImageOps
@@ -27,6 +26,12 @@ try:
         register_heif_opener()
     except:
         HAVE_HEIF = False
+
+    try:
+        Image.new("RGB", (2, 2)).save(BytesIO(), format="webp")
+        HAVE_WEBP = True
+    except:
+        HAVE_WEBP = False
 except:
     HAVE_PIL = False
 
@@ -339,7 +344,7 @@ class ThumbSrv(object):
             # thumb file
             try:
                 b64, ts, ext = f.split(".")
-                if len(b64) != 24 or len(ts) != 8 or ext != "jpg":
+                if len(b64) != 24 or len(ts) != 8 or ext not in ["jpg", "webp"]:
                     raise Exception()
 
                 ts = int(ts, 16)
diff --git a/copyparty/util.py b/copyparty/util.py
index b7152e00..35d03c56 100644
--- a/copyparty/util.py
+++ b/copyparty/util.py
@@ -34,10 +34,12 @@ if not PY2:
     from urllib.parse import unquote_to_bytes as unquote
     from urllib.parse import quote_from_bytes as quote
     from queue import Queue
+    from io import BytesIO
 else:
     from urllib import unquote  # pylint: disable=no-name-in-module
     from urllib import quote  # pylint: disable=no-name-in-module
     from Queue import Queue  # pylint: disable=import-error,no-name-in-module
+    from StringIO import StringIO as BytesIO
 
 surrogateescape.register_surrogateescape()
 FS_ENCODING = sys.getfilesystemencoding()