diff --git a/g-cloud/requirements.txt b/g-cloud/requirements.txt
index 54cb0b2..666cb59 100644
--- a/g-cloud/requirements.txt
+++ b/g-cloud/requirements.txt
@@ -131,7 +131,7 @@ lxml==4.5.0
 MarkupSafe==1.1.1
 matplotlib==3.1.3
 mccabe==0.6.1
-mistune==0.8.4
+mistune==2.0.3
 mkl-fft==1.0.15
 mkl-random==1.1.0
 mkl-service==2.3.0