diff --git a/build-constraints.yaml b/build-constraints.yaml
index 7609609e..1c7d590f 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2136,6 +2136,7 @@ packages:
         - fitspec < 0 # build failure with GHC 8.4
         - speculate
         - extrapolate
+        - percent-format
 
     "Trevor Elliott <awesomelyawesome@gmail.com> @elliottt":
         - irc