diff --git a/docs/requirements-rtd.txt b/docs/requirements-rtd.txt
index 7a84712..65a5862 100644
--- a/docs/requirements-rtd.txt
+++ b/docs/requirements-rtd.txt
@@ -8,4 +8,5 @@ pyserial>=3.5
 pyusb>=1.1.1
 PyVISA>=1.11.3
 rpyc>=5.0.1
-scipy>=1.7.0
\ No newline at end of file
+scipy>=1.7.0
+sphinxcontrib-spelling>=7.7.0
\ No newline at end of file