diff --git a/requirements.txt b/requirements.txt
index c9e8372..99ee390 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
+cairocffi==1.6.1
 CairoSVG==2.4.2
 cffi==1.14.0
 Click==7.0
@@ -13,6 +14,7 @@ Markdown==3.1.1
 markdown2==2.4.0
 MarkupSafe==1.1.1
 Pillow==7.0.0
+pkg-resources==0.0.0
 pycparser==2.19
 Pygments==2.9.0
 Pyphen==0.9.5