diff --git a/app-text/linuxdoc-tools/linuxdoc-tools-0.9.69.ebuild b/app-text/linuxdoc-tools/linuxdoc-tools-0.9.69.ebuild
index ccc6cc82e815d..11654a737f943 100644
--- a/app-text/linuxdoc-tools/linuxdoc-tools-0.9.69.ebuild
+++ b/app-text/linuxdoc-tools/linuxdoc-tools-0.9.69.ebuild
@@ -22,6 +22,7 @@ DEPEND="
 	dev-lang/perl:=
 	|| ( sys-apps/gawk sys-apps/mawk )
 	sys-apps/groff
+	sys-devel/flex
 	doc? (
 		dev-texlive/texlive-fontsrecommended
 		virtual/latex-base