diff --git a/build-constraints.yaml b/build-constraints.yaml
index 9332f23e..8015dd60 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -5228,6 +5228,7 @@ packages:
         - static-bytes
 
     "Torsten Schmits <stackage@schmits.me> @tek":
+        - exon
         - incipit-base
         - incipit-core
         - polysemy