diff --git a/build-constraints.yaml b/build-constraints.yaml
index b76ef503..ec8d4783 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -3553,6 +3553,7 @@ expected-test-failures:
     - spdx # https://github.com/phadej/spdx/issues/8
     - statistics # https://github.com/bos/statistics/issues/42
     - matplotlib # https://github.com/fpco/stackage/issues/2365
+    - mltool # https://github.com/Alexander-Ignatyev/mltool/issues/1
 
     # Timeouts
     # These tests sometimes take too long and hit the stackage build