diff --git a/source/requirements.txt b/source/requirements.txt
index b5565db..f6f30ce 100644
--- a/source/requirements.txt
+++ b/source/requirements.txt
@@ -1,4 +1,5 @@
 docutils<0.18
 ipykernel
+sphinx>5
 nbsphinx
-sphinx>5
\ No newline at end of file
+standard-imghdr
\ No newline at end of file