diff --git a/docs/doxygen.conf.tmpl b/docs/doxygen.conf.tmpl
index abfad4d..50b5955 100644
--- a/docs/doxygen.conf.tmpl
+++ b/docs/doxygen.conf.tmpl
@@ -656,6 +656,7 @@ WARN_LOGFILE           =
 # with spaces.
 
 INPUT                  = @CMAKE_SOURCE_DIR@/src \
+                         @CMAKE_SOURCE_DIR@/src/lua \
                          @CMAKE_SOURCE_DIR@/src/proc \
                          @CMAKE_SOURCE_DIR@/rules \
                          @CMAKE_SOURCE_DIR@/modules \