diff --git a/benchmark/potrf.c b/benchmark/potrf.c
index 580e46072..cb4c23bab 100644
--- a/benchmark/potrf.c
+++ b/benchmark/potrf.c
@@ -193,14 +193,14 @@ int main(int argc, char *argv[]){
 	  a[((long)j + (long)j * (long)m) * 2 + 1] = 0.;
 
 	  for(i = j + 1; i < m; i++) {
-	    a[((long)i + (long)j * (long)m) * 2 + 0] = ((double) rand() / (double) RAND_MAX) - 0.5;
+	    a[((long)i + (long)j * (long)m) * 2 + 0] = 0;
 	    a[((long)i + (long)j * (long)m) * 2 + 1] = ((double) rand() / (double) RAND_MAX) - 0.5;
 	  }
 	}
       } else {
 	for (j = 0; j < m; j++) {
 	  for(i = 0; i < j; i++) {
-	    a[((long)i + (long)j * (long)m) * 2 + 0] = ((double) rand() / (double) RAND_MAX) - 0.5;
+	    a[((long)i + (long)j * (long)m) * 2 + 0] = 0.;
 	    a[((long)i + (long)j * (long)m) * 2 + 1] = ((double) rand() / (double) RAND_MAX) - 0.5;
 	  }