diff --git a/src/gradientMex.cpp b/src/gradientMex.cpp
index 98d2882..200fe7f 100755
--- a/src/gradientMex.cpp
+++ b/src/gradientMex.cpp
@@ -285,7 +285,7 @@ void hog( float *M, float *O, float *H, int h, int w, int binSize,
 {
   float *N, *R; const int hb=h/binSize, wb=w/binSize, nb=hb*wb;
   // compute unnormalized gradient histograms
-  R = (float*) wrCalloc(wb*hb*nOrients,sizeof(float));
+  R = (float*) wrCalloc(wb*hb*nOrients+2,sizeof(float));
   gradHist( M, O, R, h, w, binSize, nOrients, softBin, full );
   // compute block normalization values
   N = hogNormMatrix( R, nOrients, hb, wb, binSize );
@@ -301,7 +301,7 @@ void fhog( float *M, float *O, float *H, int h, int w, int binSize,
   const int hb=h/binSize, wb=w/binSize, nb=hb*wb, nbo=nb*nOrients;
   float *N, *R1, *R2; int o, x;
   // compute unnormalized constrast sensitive histograms
-  R1 = (float*) wrCalloc(wb*hb*nOrients*2,sizeof(float));
+  R1 = (float*) wrCalloc(wb*hb*nOrients*2+2,sizeof(float));
   gradHist( M, O, R1, h, w, binSize, nOrients*2, softBin, true );
   // compute unnormalized contrast insensitive histograms
   R2 = (float*) wrCalloc(wb*hb*nOrients,sizeof(float));