diff --git a/requirements_dev.txt b/requirements_dev.txt
index f11086b..7d0a0be 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -1,3 +1,4 @@
 scipy
 pytest
-crackle-codec
\ No newline at end of file
+crackle-codec
+cython
\ No newline at end of file