diff --git a/tools/doxygen/README.md b/tools/doxygen/README.md
index 34d12c1d8a..d6a6646033 100644
--- a/tools/doxygen/README.md
+++ b/tools/doxygen/README.md
@@ -5,7 +5,7 @@
 
 ## Prerequisites
 
-**Doxygen** ≥ 3.9.1 - https://www.doxygen.nl/
+**Doxygen** ≥ 1.9.1 - https://www.doxygen.nl/
 
 Make a `/build/doxygen/` directory.