diff --git a/Layer.cpp b/Layer.cpp
index 28fb630..4b14db9 100644
--- a/Layer.cpp
+++ b/Layer.cpp
@@ -30,7 +30,7 @@ void Layer::feedForward(const Layer &inputLayer)
 	}
 }
 
-double Layer::getWeightedSum(int outputNeuron) const
+double Layer::getWeightedSum(size_t outputNeuron) const
 {
 	double sum = 0.0;
 
diff --git a/Layer.h b/Layer.h
index 1290a58..94bab0e 100644
--- a/Layer.h
+++ b/Layer.h
@@ -14,7 +14,7 @@ public:
 
 	void setOutputValues(const std::vector<double> & outputValues);
 	void feedForward(const Layer &inputLayer);
-	double getWeightedSum(int outputNeuron) const;
+    double getWeightedSum(size_t outputNeuron) const;
 	void connectTo(const Layer & nextLayer);
 
 	void updateInputWeights(Layer &prevLayer);
diff --git a/Neuron.cpp b/Neuron.cpp
index aa180bf..afa6a5e 100644
--- a/Neuron.cpp
+++ b/Neuron.cpp
@@ -30,7 +30,7 @@ void Neuron::feedForward(double inputValue)
 	outputValue = transferFunction(inputValue);
 }
 
-double Neuron::getWeightedOutputValue(unsigned int outputNeuron) const
+double Neuron::getWeightedOutputValue(size_t outputNeuron) const
 {
 	if (outputNeuron < outputWeights.size())
 	{
diff --git a/Neuron.h b/Neuron.h
index 8dcb5d7..20b1684 100644
--- a/Neuron.h
+++ b/Neuron.h
@@ -17,7 +17,7 @@ public:
 
 	void setOutputValue(double value);
 	void feedForward(double inputValue);
-	double getWeightedOutputValue(unsigned int outputNeuron) const;
+    double getWeightedOutputValue(size_t outputNeuron) const;
 	
 	void createRandomOutputWeights(size_t numberOfWeights);
 	void createOutputWeights(std::list<double> weights);