diff --git a/tools/constraints.txt b/tools/constraints.txt
index b1eb7ca82..b11197a8c 100644
--- a/tools/constraints.txt
+++ b/tools/constraints.txt
@@ -1 +1,4 @@
+# https://github.com/pyodide/pyodide/issues/5131
 meson < 1.6
+# https://github.com/pyodide/pyodide/issues/5221
+cysignals < 1.12.0