diff --git a/EyeRecToo/src/pupil-detection/PuRe.cpp b/EyeRecToo/src/pupil-detection/PuRe.cpp
index db12cbcc3842bc2cdf1c67f4522e81f4e25b7ff0..f8f4ebf33c25f6374a2bc9da622cde4f4b44138c 100644
--- a/EyeRecToo/src/pupil-detection/PuRe.cpp
+++ b/EyeRecToo/src/pupil-detection/PuRe.cpp
@@ -136,7 +136,6 @@ Mat PuRe::canny(const Mat& in, const bool blurImage, const bool useL2, const int
 	 * Smoothing and directional derivatives
 	 * TODO: adapt sizes to image size
 	 */
-    Mat blurred;
     if (blurImage) {
         Size blurSize(5, 5);
         GaussianBlur(in, blurred, blurSize, 1.5, 1.5, BORDER_REPLICATE);
@@ -715,6 +714,7 @@ Pupil PuRe::implDetect(const cv::Mat& frame, cv::Rect roi, const float& userMinP
     workingSize.height = input.rows;
 
     // Preallocate stuff for edge detection
+    blurred = Mat::zeros(workingSize, CV_8U);
     dx = Mat::zeros(workingSize, CV_32F);
     dy = Mat::zeros(workingSize, CV_32F);
     magnitude = Mat::zeros(workingSize, CV_32F);
diff --git a/EyeRecToo/src/pupil-detection/PuRe.h b/EyeRecToo/src/pupil-detection/PuRe.h
index 51dfb9720773a0a3e86fc0397265b20279bf0940..9ab8a95a3e722479e077a66347065108ef5e436a 100644
--- a/EyeRecToo/src/pupil-detection/PuRe.h
+++ b/EyeRecToo/src/pupil-detection/PuRe.h
@@ -208,7 +208,7 @@ protected:
     void detect(Pupil& pupil);
 
     // Canny
-    cv::Mat dx, dy, magnitude;
+    cv::Mat blurred, dx, dy, magnitude;
     cv::Mat edgeType, edge;
     cv::Mat canny(const cv::Mat& in, const bool blur = true, const bool useL2 = true, const int bins = 64, const float nonEdgePixelsRatio = 0.7f, const float lowHighThresholdRatio = 0.4f);