diff --git a/setup.py b/setup.py
index 075bc88c..78323b62 100644
--- a/setup.py
+++ b/setup.py
@@ -127,6 +127,7 @@
             'pyVCF',
             'mhcflurry<=1.4.3',
             'mhcnuggets',
+            'keras<=2.3.1',         # legacy tensorflow required by mhcnuggets resolves to incompatible keras version
             'h5py<=2.10.0',         # mhcnuggets fails to read model with newer versions
             ],