diff --git a/setup.py b/setup.py
index 4ac6d96..0c8779b 100644
--- a/setup.py
+++ b/setup.py
@@ -45,7 +45,7 @@
     include_package_data=True,
     install_requires=[
         "pytket ~= 1.23.0rc0",
-        "pyquil ~= 3.5",
+        "pyquil >= 3.5,< 5.0",
         "typing-extensions ~= 4.2",
     ],
     classifiers=[