diff --git a/branches/ParadisEO-GPU/src/GPUType/moGPURealVector.h b/branches/ParadisEO-GPU/src/GPUType/moGPURealVector.h
index 786ea60aa..2a8b2bebe 100644
--- a/branches/ParadisEO-GPU/src/GPUType/moGPURealVector.h
+++ b/branches/ParadisEO-GPU/src/GPUType/moGPURealVector.h
@@ -108,13 +108,13 @@ public:
 	 * Write object. Called printOn since it prints the object _on_ a stream.
 	 * @param _os A std::ostream.
 	 */
-	void printOn(std::ostream& os) const {
-		EO<Fitness>::printOn(os);
-		os << ' ';
-		os << N << ' ';
+	void printOn(std::ostream& _os) const {
+		EO<Fitness>::printOn(_os);
+		_os << ' ';
+		_os << N << ' ';
 		unsigned int i;
 		for (i = 0; i < N; i++)
-		os << vect[i] << ' ';
+		_os << vect[i] << ' ';
 
 	}