diff --git a/crypto_kem/frodokem640shake/clean/kem.c b/crypto_kem/frodokem640shake/clean/kem.c
index 20803408..8dd0ba2e 100644
--- a/crypto_kem/frodokem640shake/clean/kem.c
+++ b/crypto_kem/frodokem640shake/clean/kem.c
@@ -55,7 +55,7 @@ int PQCLEAN_FRODOKEM640SHAKE_CLEAN_crypto_kem_keypair(unsigned char *pk, unsigne
     memcpy(sk_s, randomness_s, CRYPTO_BYTES);
     memcpy(sk_pk, pk, CRYPTO_PUBLICKEYBYTES);
     for (size_t i = 0; i < PARAMS_N * PARAMS_NBAR; i++) {
-        sk_S[i] = PQCLEAN_FRODOKEM640SHAKE_CLEAN_UINT16_TO_LE(sk_S[i]);
+        S[i] = PQCLEAN_FRODOKEM640SHAKE_CLEAN_UINT16_TO_LE(S[i]);
     }
     memcpy(sk_S, S, 2 * PARAMS_N * PARAMS_NBAR);
 
diff --git a/crypto_kem/frodokem640shake/clean/matrix_shake.c b/crypto_kem/frodokem640shake/clean/matrix_shake.c
index 44be64a3..e21d2bc8 100644
--- a/crypto_kem/frodokem640shake/clean/matrix_shake.c
+++ b/crypto_kem/frodokem640shake/clean/matrix_shake.c
@@ -17,7 +17,7 @@ int PQCLEAN_FRODOKEM640SHAKE_CLEAN_mul_add_as_plus_e(uint16_t *out, const uint16
     // Generate-and-multiply: generate matrix A (N x N) row-wise, multiply by s on the right.
     // Inputs: s, e (N x N_BAR)
     // Output: out = A*s + e (N x N_BAR)
-    int i, j, k;
+    uint16_t i, j, k;
     int16_t A[PARAMS_N * PARAMS_N] = {0};
 
     uint8_t seed_A_separated[2 + BYTES_SEED_A];
@@ -50,7 +50,7 @@ int PQCLEAN_FRODOKEM640SHAKE_CLEAN_mul_add_sa_plus_e(uint16_t *out, const uint16
     // Generate-and-multiply: generate matrix A (N x N) column-wise, multiply by s' on the left.
     // Inputs: s', e' (N_BAR x N)
     // Output: out = s'*A + e' (N_BAR x N)
-    int i, j, k;
+    uint16_t i, j, k;
     int16_t A[PARAMS_N * PARAMS_N] = {0};
 
     uint8_t seed_A_separated[2 + BYTES_SEED_A];