diff --git a/build-constraints.yaml b/build-constraints.yaml
index b4baa4b6..56b6e40c 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -3122,6 +3122,7 @@ packages:
 
     "Alexander Ignatyev <ignatyev.alexander@gmail.com> @alexander-ignatyev":
         - astro
+        - mltool
 
     # If you stop maintaining a package you can move it here.
     # It will then be disabled if it starts causing problems.
@@ -3553,6 +3554,7 @@ 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