diff --git a/pyproject.toml b/pyproject.toml
index 289b2253..9cb20e71 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -26,9 +26,9 @@ classifiers = [
 dependencies = [
     "docutils",
     # Keep in sync with Furo's constraint.
-    "sphinx>=6.0",
+    "sphinx>=6.0,<8.0",
     # See CONTRIBUTING.md for how to upgrade Furo.
-    "furo==2023.8.19",
+    "furo==2024.1.29",
 ]
 
 [project.entry-points."sphinx.html_themes"]