diff --git a/build-constraints.yaml b/build-constraints.yaml
index 292447eb..7e687160 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -7879,6 +7879,9 @@ packages:
 
         # https://github.com/commercialhaskell/stackage/issues/7939
         - fixed-vector < 2.1
+
+        # https://github.com/commercialhaskell/stackage/issues/7940
+        - json-spec < 1.2
     # end of Stackage upper bounds
 # end of packages