diff --git a/.travis-ci.sh b/.travis-ci.sh
index 8e0e8ef..77c138b 100755
--- a/.travis-ci.sh
+++ b/.travis-ci.sh
@@ -1,4 +1,4 @@
-OPAM_DEPENDS="lwt ssl cohttp atdgen yojson cmdliner lambda-term uri"
+OPAM_DEPENDS="lwt ssl cohttp atdgen yojson cmdliner lambda-term uri stringext"
 
 case "$OCAML_VERSION,$OPAM_VERSION" in
 4.00.1,1.0.0) ppa=avsm/ocaml40+opam10 ;;