diff --git a/tox.ini b/tox.ini
index bccbb14edc..7e28fc6f3b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,6 +7,7 @@ skipsdist = True
 setenv =
    VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/test-requirements.txt
+whitelist_externals = bash
 
 [testenv:venv]
 commands = {posargs}
@@ -15,7 +16,10 @@ commands = {posargs}
 commands = openstack-doc-test --check-niceness {posargs}
 
 [testenv:checksyntax]
-commands = openstack-doc-test --check-syntax {posargs}
+commands =
+    openstack-doc-test --check-syntax {posargs}
+    # Check that .po and .pot files are valid:
+    bash -c "find doc -type f -regex '.*\.pot?' -print0|xargs --null -n 1 msgfmt --check-format -o /dev/null"
 
 [testenv:checkdeletions]
 commands = openstack-doc-test --check-deletions {posargs}