diff --git a/dune-project b/dune-project
index 2e8e093717..27fa5d92a7 100644
--- a/dune-project
+++ b/dune-project
@@ -1,3 +1,3 @@
 (lang dune 1.8)
 (name irmin)
-(using fmt 1.2)
+(using fmt 1.1)