diff --git a/docs/doxygen.cfg b/docs/doxygen.cfg
index 52a0c4c..46bad0a 100644
--- a/docs/doxygen.cfg
+++ b/docs/doxygen.cfg
@@ -411,7 +411,7 @@
 # the COLS_IN_ALPHA_INDEX tag can be used to specify the number of columns 
 # in which this list will be split (can be a number in the range [1..20])
 
-COLS_IN_ALPHA_INDEX    = 5
+COLS_IN_ALPHA_INDEX    = 4
 
 # In case all classes in a project start with a common prefix, all 
 # classes will be put under the same header in the alphabetical index.