diff --git a/skopt/space/transformers.py b/skopt/space/transformers.py
index 68892952..87cc3b68 100644
--- a/skopt/space/transformers.py
+++ b/skopt/space/transformers.py
@@ -259,7 +259,7 @@ def transform(self, X):
         if (self.high - self.low) == 0.:
             return X * 0.
         if self.is_int:
-            return (np.round(X).astype(np.int) - self.low) /\
+            return (np.round(X).astype(np.int64) - self.low) /\
                    (self.high - self.low)
         else:
             return (X - self.low) / (self.high - self.low)
@@ -272,7 +272,7 @@ def inverse_transform(self, X):
             raise ValueError("All values should be greater than 0.0")
         X_orig = X * (self.high - self.low) + self.low
         if self.is_int:
-            return np.round(X_orig).astype(np.int)
+            return np.round(X_orig).astype(np.int64)
         return X_orig