diff --git a/requirements.txt b/requirements.txt
index f0f2c057..6301021e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -21,3 +21,4 @@ nose==1.3.7
 cardboardlint==1.3.0
 pylint==2.5.3
 gdown
+cython
diff --git a/requirements_tests.txt b/requirements_tests.txt
index f37cda19..4e7f3435 100644
--- a/requirements_tests.txt
+++ b/requirements_tests.txt
@@ -18,3 +18,4 @@ bokeh==1.4.0
 soundfile
 nose==1.3.7
 cardboardlint==1.3.0
+cython
\ No newline at end of file