diff --git a/.travis/autobrew.py b/.travis/autobrew.py
index 1ef5dfb9..1a477206 100644
--- a/.travis/autobrew.py
+++ b/.travis/autobrew.py
@@ -15,6 +15,7 @@ class Ocrmypdf < Formula
   ${ocrmypdf_sha256}
 
   depends_on :python3
+  depends_on :x11  # Pillow needs XQuartz
   depends_on "pkg-config" => :build
   depends_on "libffi"
   depends_on "tesseract"