diff --git a/esp32/scripts/generate_cert_bundle.py b/esp32/scripts/generate_cert_bundle.py
index 2aca225..ffc2e19 100644
--- a/esp32/scripts/generate_cert_bundle.py
+++ b/esp32/scripts/generate_cert_bundle.py
@@ -28,6 +28,9 @@ try:
     from cryptography.hazmat.primitives import serialization
 except ImportError:
     env.Execute("$PYTHONEXE -m pip install cryptography")
+    from cryptography import x509
+    from cryptography.hazmat.backends import default_backend
+    from cryptography.hazmat.primitives import serialization
 
 
 ca_bundle_bin_file = 'x509_crt_bundle.bin'