diff --git a/requirements.txt b/requirements.txt
index af16adb0e..4b938908c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,5 +11,5 @@ jupyter
 funcsigs
 jupyter
 sphinx-rtd-theme
-nbsphinx
+nbsphinx==0.4.3
 recommonmark