diff --git a/pyproject.toml b/pyproject.toml
index 9fd98ac6..2e6d2238 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,7 +46,7 @@ doc = [
 ]
 test = [
     "pytest",
-    "tornado>=4.5",
+    "tornado>=6.0",
     "typeguard",
 ]
 
@@ -54,7 +54,7 @@ test = [
 dev = [
     "poethepoet",
     "pytest",
-    "tornado>=4.5",
+    "tornado>=6.0",
     "typeguard",
     "ruff",
     "mypy",