diff --git a/build-constraints.yaml b/build-constraints.yaml
index 0feca35f..292447eb 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -7876,6 +7876,9 @@ packages:
 
         # https://github.com/commercialhaskell/stackage/issues/7938
         - citeproc < 0.13
+
+        # https://github.com/commercialhaskell/stackage/issues/7939
+        - fixed-vector < 2.1
     # end of Stackage upper bounds
 # end of packages