diff --git a/tools/travis-ci.sh b/tools/travis-ci.sh
index d1570c1..c003998 100644
--- a/tools/travis-ci.sh
+++ b/tools/travis-ci.sh
@@ -1,4 +1,7 @@
 #!/bin/bash -e
+# Show the revision of all submodules
+git submodule foreach git rev-parse HEAD
+
 # Install some dependencies manually
 DEPS_DIR="${HOME}/deps"
 mkdir -p ${DEPS_DIR}