diff --git a/evolutionary_search/__init__.py b/evolutionary_search/__init__.py
index b12a03f..3fee5ef 100644
--- a/evolutionary_search/__init__.py
+++ b/evolutionary_search/__init__.py
@@ -282,7 +282,7 @@ def __init__(self, estimator, params, scoring=None, cv=4,
 
     def fit(self, X, y=None):
         self.best_estimator_ = None
-        self.best_score_ = -1
+        self.best_score_ = float("-inf")
         self.best_params_ = None
         for possible_params in self.possible_params:
             self._fit(X, y, possible_params)