diff --git a/setup.py b/setup.py
index 97c1275..3cccdd4 100644
--- a/setup.py
+++ b/setup.py
@@ -86,7 +86,7 @@
 __requires__ = [
     'setuptools',
     'numpy',
-    'pillow>=3.4.0',
+    'pillow>=3.4.0,<10.0.0',
     'colorzero>=1.1',
 ]