diff --git a/build-constraints.yaml b/build-constraints.yaml
index f84a0df1..14d7a7ae 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2134,6 +2134,7 @@ packages:
         - fitspec < 0 # build failure with GHC 8.4
         - speculate
         - extrapolate
+        - percent-format
 
     "Trevor Elliott <awesomelyawesome@gmail.com> @elliottt":
         - irc