diff --git a/docs/INSTALL.rst b/docs/INSTALL.rst
index f9492db..9f0f02b 100644
--- a/docs/INSTALL.rst
+++ b/docs/INSTALL.rst
@@ -85,7 +85,7 @@
 
 - doxygen
 - graphviz
-- sphinx >= 1.3
+- sphinx >= 4.0
 - sphinxcontrib-doxylink
 
 The following lists the steps to install these prerequisites on various common platforms.