diff --git a/build-constraints.yaml b/build-constraints.yaml
index c9f083b2..68767e07 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -4375,7 +4375,7 @@ packages:
         - natural-sort
 
     "John Biesnecker <jbiesnecker@gmail.com> @biesnecker":
-        - async-pool
+        - async-pool < 0 # https://github.com/jwiegley/async-pool/issues/28
 
     "Zoltan Kelemen <kelemzol@elte.hu> @kelemzol":
         - fswatch