diff --git a/sys/crypto/armv8/armv8_crypto.h b/sys/crypto/armv8/armv8_crypto.h
--- a/sys/crypto/armv8/armv8_crypto.h
+++ b/sys/crypto/armv8/armv8_crypto.h
@@ -73,12 +73,12 @@
     struct crypto_buffer_cursor *, struct crypto_buffer_cursor *,
     size_t, const uint8_t *,
     uint8_t tag[static GMAC_DIGEST_LEN],
-    const uint8_t[static AES_BLOCK_LEN],
+    const uint8_t[static AES_GCM_IV_LEN],
     const __uint128_val_t *);
 int armv8_aes_decrypt_gcm(AES_key_t *, size_t,
     struct crypto_buffer_cursor *, struct crypto_buffer_cursor *,
     size_t, const uint8_t *, const uint8_t tag[static GMAC_DIGEST_LEN],
-    const uint8_t[static AES_BLOCK_LEN],
+    const uint8_t[static AES_GCM_IV_LEN],
     const __uint128_val_t *);
 
 void armv8_aes_encrypt_xts(AES_key_t *, const void *, size_t,