diff --git a/build-constraints.yaml b/build-constraints.yaml
index 007d8efa..b5931a8c 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2962,7 +2962,7 @@ packages:
     "Michal Konecny <mikkonecny@gmail.com> @michalkonecny":
         - hmpfr
         - mixed-types-num
-        - aern2-mp
+        - aern2-mp < 0 # https://github.com/michalkonecny/aern2/issues/1
         - aern2-real < 0
 
     "Bartosz Nitka <niteria@gmail.com> @niteria":