diff --git a/.readthedocs.yml b/.readthedocs.yml
index fe0cdaec..614f5031 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -20,6 +20,7 @@ build:
       - make
       - make install
       - tree ./install
+      - pip install cffi
       - python ./python/src/libcpuid/_ffi_build_manual.py ./libcpuid/libcpuid.h ./install/include
 
 sphinx: