diff --git a/doc/Doxyfile b/doc/Doxyfile
index 9333f3eeb9e0dd52fbfada09185c3882e105b668..940c4dab78e65004a9663ac0cf318a086ff69a0e 100644
--- a/doc/Doxyfile
+++ b/doc/Doxyfile
@@ -366,6 +366,7 @@ INPUT                  = mainpage \
                          ../fem \
                          ../common \
                          ../solver \
+                         ../istl \
                          ../io \
                          ../lib/io