diff --git a/pyproject.toml b/pyproject.toml
index 0bbd5af..8f4dd18 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,6 +12,7 @@ dependencies = [
     "flask_sqlalchemy>=3.0,<4",
     "flask-nav-0.6.0",
     "flask-wtf>=1.2.2,<2",
+    "pyzotero>=1.6.11,<2",
     ]
 
 [project.optional-dependencies]