diff --git a/tox.ini b/tox.ini
index 3207bd4..7c03544 100644
--- a/tox.ini
+++ b/tox.ini
@@ -44,9 +44,12 @@ envdir = {toxworkdir}/api-ref
 whitelist_externals =
   rm
   make
+  sh
 commands =
   rm -rf api-ref/build/pdf
   sphinx-build -a -E -W -b latex api-ref/source api-ref/build/pdf
+  sh -c "for f in api-ref/build/pdf/*.gif; do gif2png -dprsO $f; done || true"
+  sh -c "for f in api-ref/build/pdf/*.tex; do sed -iorig 's/\.gif//g' $f; done"
   make -C api-ref/build/pdf
 
 [testenv:umn]