diff --git a/setup.py b/setup.py
index dc54029..3a3772d 100644
--- a/setup.py
+++ b/setup.py
@@ -27,7 +27,7 @@ def read(*parts):
             'tests',
         )
     ),
-    install_requires=["pynamodb>=5.0.0"],
+    install_requires=["pynamodb>=5.0.0,<6.0.0"],
     include_package_data=True,
     python_requires=">=3.6",
     license="MIT",