diff --git a/build-constraints.yaml b/build-constraints.yaml
index 52daeec2..b408e80d 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -3166,6 +3166,9 @@ packages:
         # https://github.com/fpco/stackage/issues/2505
         - one-liner < 0.9
 
+        # https://github.com/fpco/stackage/issues/2507
+        - concurrent-output < 1.9
+
 # end of packages
 
 # Package flags are applied to individual packages, and override the values of