diff --git a/example/ex-array04.c b/example/ex-array04.c
index f2f07a1b..8987845d 100644
--- a/example/ex-array04.c
+++ b/example/ex-array04.c
@@ -3,7 +3,9 @@
 #include "m-array.h"
 #include "m-algo.h"
 
+/* Define an array of mpz_t */
 ARRAY_DEF(array_mpz, mpz_t, M_CLASSIC_OPLIST(mpz))
+/* Define some algorithm functions on array_mpz_t */
 ALGO_DEF(array_mpz, ARRAY_OPLIST(array_mpz, M_CLASSIC_OPLIST(mpz)))
 
 static inline void my_mpz_inc(mpz_t *d, const mpz_t a){
@@ -19,14 +21,17 @@ int main(void)
   mpz_init_set_ui(z, 1);
   array_mpz_t a;
   array_mpz_init(a);
+
   array_mpz_push_back(a, z);
   for(size_t i = 2 ; i < 1000; i++) {
     mpz_mul_ui(z, z, i);
     array_mpz_push_back(a, z);    
   }
-  /* z = sum (a[i]^2) */
+
+  /* Compute z = sum (a[i]^2) */
   array_mpz_map_reduce (&z, a, my_mpz_inc, my_mpz_sqr);
   gmp_printf ("Z=%Zd\n", z);
+
   array_mpz_clear(a);
   mpz_clear(z);
 }