diff --git a/doc/doxygen/Doxyfile b/doc/doxygen/Doxyfile
index 493f3377ec..d7709c9579 100644
--- a/doc/doxygen/Doxyfile
+++ b/doc/doxygen/Doxyfile
@@ -34,7 +34,7 @@ PROJECT_NAME           = Cantera
 # This could be handy for archiving the generated documentation or
 # if some version control system is used.
 
-PROJECT_NUMBER         = 2.0
+PROJECT_NUMBER         = 2.1.1
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute)
 # base path where the generated documentation will be put.