diff --git a/setup.py b/setup.py
index d628f08..ff73153 100755
--- a/setup.py
+++ b/setup.py
@@ -39,17 +39,17 @@
     packages=setuptools.find_packages(),
     package_data={'MonoTools': extrafiles},
     install_requires=['matplotlib',
-                      'numpy',
+                      'numpy==1.21',
                       'pandas',
                       'scipy',
                       'astropy',
                       'astroquery',
                       'batman-package',
                       'lightkurve==1.11.0',
-                      'arviz',
-                      'pymc',
-					  'pymc_ext',
-                      'exoplanet[pymc]',
+                      'arviz==0.11',
+                      'pymc3==3.8',
+					  'pymc3_ext',
+                      'exoplanet',
                       'celerite2',
                       'requests',
                       'urllib3',