diff --git a/setup.py b/setup.py
index 8e479ea4b..b2090f124 100644
--- a/setup.py
+++ b/setup.py
@@ -21,7 +21,7 @@
       package_dir={'qctoolkit': 'qctoolkit'},
       packages=packages,
       tests_require=['pytest'],
-      install_requires=['sympy>=1.1.1', 'numpy'] + requires_typing,
+      install_requires=['sympy==1.1.1', 'numpy'] + requires_typing,
       extras_require={
           'testing': ['pytest'],
           'plotting': ['matplotlib'],