1 files changed, 3 insertions, 1 deletions
diff --git a/src/cos.c b/src/cos.c
index 8f58e8e85..7336bb860 100644
--- a/src/cos.c
+++ b/src/cos.c
@@ -64,7 +64,9 @@ mpfr_cos2_aux (mpfr_ptr f, mpfr_srcptr r)
   mpz_init (t);
   ex = mpfr_get_z_2exp (x, r); /* r = x*2^ex */
 
-  /* remove trailing zeroes */
+  /* Remove trailing zeroes.
+     Since x comes from a MPFR number, due to the constrainst on the exponent
+     and the precision, there can be no integer overflow below. */
   l = mpz_scan1 (x, 0);
   ex += l;
   mpz_fdiv_q_2exp (x, x, l);