diff --git a/requirements.txt b/requirements.txt
index 853d485..4dcd662 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,6 +5,6 @@ networkx>=2.2
 scikit-learn>=0.20.0
 tabulate>=0.8.2
 tqdm>=4.26.0
-cvxpy # for preimage.
-cvxopt # for preimage.
-mosek # for preimage.
+cvxpy>=1.0.31 # for preimage.
+cvxopt>=1.2.5 # for preimage.
+mosek>=9.2.5 # for preimage.