diff --git a/libkmod/docs/Makefile.am b/libkmod/docs/Makefile.am
index 06f65c8..c4f3d69 100644
--- a/libkmod/docs/Makefile.am
+++ b/libkmod/docs/Makefile.am
@@ -25,8 +25,10 @@
 
 content_files = version.xml
 
+EXTRA_DIST =
+
 if ENABLE_GTK_DOC
 include $(top_srcdir)/libkmod/docs/gtk-doc.make
 else
-EXTRA_DIST = libkmod-docs.xml libkmod-sections.txt
+EXTRA_DIST += libkmod-docs.xml libkmod-sections.txt
 endif