diff --git a/src/DataSet/DataSet.cpp b/src/DataSet/DataSet.cpp
index 71b288468a3e3da0024f2a7b78b912a3fdafbe90..2e9dfe5f3ff84586f4868a6beb71e451b7905b8a 100644
--- a/src/DataSet/DataSet.cpp
+++ b/src/DataSet/DataSet.cpp
@@ -368,6 +368,9 @@ namespace lib4neuro {
             }
             pair.second = tmp_out;
         }
+
+        /* Remove found max and minimal values, because of is_normalized() method */
+        this->max_min_inp_val.clear();
     }
 
     void DataSet::de_normalize_single(std::vector<double> &d1, std::vector<double> &d2){