diff --git a/app/models/problem.py b/app/models/problem.py
index f09812e..a520813 100644
--- a/app/models/problem.py
+++ b/app/models/problem.py
@@ -3,7 +3,7 @@ from typing import TYPE_CHECKING
 
 from pydantic import BaseModel
 from typing import Any, List
-from pulp import LpProblem, LpVariable, LpStatus, lpSum
+from pulp import LpProblem, LpVariable, LpStatus, lpSum, COIN
 
 import logging
 
@@ -46,7 +46,7 @@ class Problem(BaseModel):
 
         # creating problem multi-objective functions
         objective_functions = solver_run.objective_function.for_problem(self, solver_run)
-        self.problem.sequentialSolve(objective_functions, None, None, pulp.COIN(gapRel=0.2, timeLimit=300))
+        self.problem.sequentialSolve(objective_functions, None, None, COIN(gapRel=0.2, timeLimit=300))
 
         return self.problem