diff --git a/posts.yaml b/posts.yaml
index 82fa05c..d1ea01a 100644
--- a/posts.yaml
+++ b/posts.yaml
@@ -1,6 +1,6 @@
 - file: posts/follow-up-mapm.md
   title: "Follow up on mapM_"
-  day: 2017-01-20
+  day: 2017-01-19
 - file: posts/safe-prelude-a-thought-experiment.md
   title: "safe-prelude: a thought experiment"
   day: 2017-01-16