diff --git a/build-constraints.yaml b/build-constraints.yaml
index 8657ff32..a0d0652b 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -808,6 +808,9 @@ packages:
         # https://github.com/fpco/stackage/issues/484
         - opaleye < 0.3.1.1
 
+        # https://github.com/fpco/stackage/issues/485
+        - parsec < 3.1.9
+
 # Package flags are applied to individual packages, and override the values of
 # global-flags
 package-flags: