diff --git a/miplearn/components/primal.py b/miplearn/components/primal.py
index 4a9f4b3..6c2cc84 100644
--- a/miplearn/components/primal.py
+++ b/miplearn/components/primal.py
@@ -119,6 +119,8 @@ class PrimalSolutionComponent(Component):
             vars_all, vars_one, vars_zero = set(), set(), set()
             pred_one_positive, pred_zero_positive = set(), set()
             for (varname, var_dict) in solution_actual.items():
+                if varname not in solution_pred.keys():
+                    continue
                 for (idx, value) in var_dict.items():
                     vars_all.add((varname, idx))
                     if value > 0.5: