diff --git a/overrides/build-systems.json b/overrides/build-systems.json
index 8c0bb9d..7969bbf 100644
--- a/overrides/build-systems.json
+++ b/overrides/build-systems.json
@@ -285,6 +285,9 @@
   "cysimdjson": [
     "cython"
   ],
+  "cytoolz": [
+    "cython"
+  ],
   "darglint": [
     "poetry"
   ],