diff --git a/doc/requirements.txt b/doc/requirements.txt
index 93d6ea70a..b715e59f5 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,4 +1,8 @@
 # These packages are required for building the documentation.
-sphinx>=4.0.0
+sphinx>=4.0.0,<7
 sphinx_autodoc_typehints>=1.4.0
 sphinx-rtd-theme>=0.4.3
+
+yara-python
+pycryptodome
+pefile