diff --git a/benchmark/gesv.c b/benchmark/gesv.c
index 26ff8bc1a..80f644e69 100644
--- a/benchmark/gesv.c
+++ b/benchmark/gesv.c
@@ -177,20 +177,20 @@ int main(int argc, char *argv[]){
 
     for(j = 0; j < m; j++){
       for(i = 0; i < m * COMPSIZE; i++){
-	a[i + j * m * COMPSIZE] = ((FLOAT) rand() / (FLOAT) RAND_MAX) - 0.5;
+	a[(long)i + (long)j * (long)m * COMPSIZE] = ((FLOAT) rand() / (FLOAT) RAND_MAX) - 0.5;
       }
     }
 
     for(j = 0; j < m; j++){
       for(i = 0; i < m * COMPSIZE; i++){
-	b[i + j * m * COMPSIZE] = 0.0;
+	b[(long)i + (long)j * (long)m * COMPSIZE] = 0.0;
       }
     }
 
 
     for (j = 0; j < m; ++j) {
       for (i = 0; i < m * COMPSIZE; ++i) {
-	b[i] += a[i + j * m * COMPSIZE];
+	b[i] += a[(long)i + (long)j * (long)m * COMPSIZE];
       }
     }