diff --git a/3rdparty/Makefile.am b/3rdparty/Makefile.am
index bcc195b13c..e21e1cbc01 100644
--- a/3rdparty/Makefile.am
+++ b/3rdparty/Makefile.am
@@ -1,6 +1,6 @@
 include $(top_srcdir)/config/common.am
 
-DIST_SUBDIRS = boost hunspell mythes libiconv zlib
+DIST_SUBDIRS = boost dtl hunspell mythes libiconv zlib
 
 if USE_INCLUDED_BOOST
 if LYX_USE_STD_REGEX