diff --git a/src/Network/NeuralNetwork.cpp b/src/Network/NeuralNetwork.cpp
index ac4caafc4351128ae71361924e47f241311d28ba..ee9fb4739242b171b09f4b1edc826d3c56eae023 100644
--- a/src/Network/NeuralNetwork.cpp
+++ b/src/Network/NeuralNetwork.cpp
@@ -465,14 +465,14 @@ namespace lib4neuro {
             THROW_INVALID_ARGUMENT_ERROR("Input and output neurons have not been specified!");
         }
 
-
         if (this->input_neuron_indices->size() != input.size()) {
-            THROW_INVALID_ARGUMENT_ERROR("Error: input size != Network input size");
+            THROW_INVALID_ARGUMENT_ERROR("Data input size != Network input size");
         }
 
         if (this->output_neuron_indices->size() != output.size()) {
-            THROW_INVALID_ARGUMENT_ERROR("Error: output size != Network output size");
+            THROW_INVALID_ARGUMENT_ERROR("Data output size != Network output size");
         }
+
         double potential, bias;
         int bias_idx;