diff --git a/build-constraints.yaml b/build-constraints.yaml
index 317264f3..07b24531 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -4711,7 +4711,7 @@ packages:
         - elynx-markov
         - elynx-nexus
         - elynx-seq
-        - elynx-tools
+        - elynx-tools < 0 # https://github.com/dschrempf/elynx/issues/3
         - elynx-tree
         - glasso
         - mcmc
@@ -9409,6 +9409,7 @@ skipped-tests:
     - egison-pattern-src-th-mode # tried egison-pattern-src-th-mode-0.2.1.2, but its *test-suite* requires the disabled package: tasty
     - either # tried either-5.0.2, but its *test-suite* requires the disabled package: test-framework
     - elliptic-curve # tried elliptic-curve-0.3.0, but its *test-suite* requires the disabled package: tasty
+    - elynx-seq # tried elynx-seq-0.7.2.1, but its *test-suite* requires the disabled package: elynx-tools
     - email-validate # tried email-validate-2.3.2.18, but its *test-suite* requires doctest >=0.8 && < 0.21 and the snapshot contains doctest-0.21.1
     - email-validate # tried email-validate-2.3.2.18, but its *test-suite* requires hspec >=2.2.3 && < 2.11 and the snapshot contains hspec-2.11.1
     - emd # tried emd-0.2.0.0, but its *test-suite* requires the disabled package: tasty