diff --git a/mp_prime_extra_strong_lucas.c b/mp_prime_extra_strong_lucas.c
index b9173afb..8cad30a7 100644
--- a/mp_prime_extra_strong_lucas.c
+++ b/mp_prime_extra_strong_lucas.c
@@ -37,6 +37,7 @@ mp_err mp_prime_extra_strong_lucas(const mp_int *N, bool *result)
    mp_int Dz, s, Vk, Vk1, tmp1, Nm2;
    uint32_t D, P;
    int32_t j, r, nbits;
+   int i;
    mp_err err = MP_OKAY;
 
    *result = false;
@@ -83,7 +84,7 @@ mp_err mp_prime_extra_strong_lucas(const mp_int *N, bool *result)
    mp_set_u32(&Vk1, P);
    nbits = mp_count_bits(&s);
    /* Compute Lucas sequence of V */
-   for (int i = nbits; i >= 0; i--) {
+   for (i = nbits; i >= 0; i--) {
       if ((err = mp_mul(&Vk, &Vk1, &tmp1)) != MP_OKAY)                               goto LTM_ERR;
       if ((err = mp_add(&tmp1, N, &tmp1)) != MP_OKAY)                                goto LTM_ERR;
       if ((err = mp_sub_d(&tmp1, P, &tmp1)) != MP_OKAY)                              goto LTM_ERR;
@@ -114,7 +115,7 @@ mp_err mp_prime_extra_strong_lucas(const mp_int *N, bool *result)
       }
    }
    /* Check for V_{2^t k} = 0 mod N for some t 0 <= t < r - 1  ([3])*/
-   for (int i = 0; i < (r - 1); i++) {
+   for (i = 0; i < (r - 1); i++) {
       if (mp_iszero(&Vk)) {
          *result = true;
          goto LTM_ERR;