diff --git a/doc/Doxyfile b/doc/Doxyfile
index 921c98c6..5006795d 100644
--- a/doc/Doxyfile
+++ b/doc/Doxyfile
@@ -31,7 +31,7 @@ PROJECT_NAME           = IPhreeqc
 # This could be handy for archiving the generated documentation or 
 # if some version control system is used.
 
-PROJECT_NUMBER         = 2.17
+PROJECT_NUMBER         = 2.18
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute) 
 # base path where the generated documentation will be put.