diff --git a/Chapter4_StructureFromMotion/GPUSURFFeatureMatcher.cpp b/Chapter4_StructureFromMotion/GPUSURFFeatureMatcher.cpp
index d380dfb..37e2842 100755
--- a/Chapter4_StructureFromMotion/GPUSURFFeatureMatcher.cpp
+++ b/Chapter4_StructureFromMotion/GPUSURFFeatureMatcher.cpp
@@ -20,6 +20,7 @@
 
 using namespace std;
 using namespace cv;
+using namespace cv::core;
 using namespace cv::gpu;
 
 //c'tor
@@ -27,7 +28,7 @@ GPUSURFFeatureMatcher::GPUSURFFeatureMatcher(vector<cv::Mat>& imgs_,
 									   vector<std::vector<cv::KeyPoint> >& imgpts_) :
 	imgpts(imgpts_),use_ratio_test(true)
 {
-	cv::gpu::printShortCudaDeviceInfo(cv::gpu::getDevice());
+	printShortCudaDeviceInfo(cv::gpu::getDevice());
 
 	extractor = new gpu::SURF_GPU();
 	
@@ -102,4 +103,4 @@ void GPUSURFFeatureMatcher::MatchFeatures(int idx_i, int idx_j, vector<DMatch>*
 			CV_PROFILE("match",matcher.match( descriptors_1, descriptors_2, *matches );)
 		}
 	}
-}
\ No newline at end of file
+}