diff --git a/docs/requirements.txt b/docs/requirements.txt
index 7ce27ed18d..e1b2384bb0 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -4,8 +4,8 @@
 sphinx>=1.8.4
 breathe==4.11.1
 sphinx-rtd-theme
-sphinxcontrib-blockdiag>=1.5.5
-sphinxcontrib-seqdiag>=0.8.5
-sphinxcontrib-actdiag>=0.8.5
-sphinxcontrib-nwdiag>=0.9.5
-recommonmark
\ No newline at end of file
+sphinxcontrib-blockdiag>=1.5.5, <2.0.0
+sphinxcontrib-seqdiag>=0.8.5, <2.0.0
+sphinxcontrib-actdiag>=0.8.5, <2.0.0
+sphinxcontrib-nwdiag>=0.9.5, <2.0.0
+recommonmark