diff --git a/tests/suites/test_suite_cipher.chachapoly.data b/tests/suites/test_suite_cipher.chachapoly.data
index de5b3d6..d91dc24 100644
--- a/tests/suites/test_suite_cipher.chachapoly.data
+++ b/tests/suites/test_suite_cipher.chachapoly.data
@@ -109,3 +109,11 @@
 ChaCha20+Poly1305 Encrypt and decrypt 32 bytes in multiple parts
 depends_on:MBEDTLS_CHACHAPOLY_C
 enc_dec_buf_multipart:MBEDTLS_CIPHER_CHACHA20_POLY1305:256:16:16:-1:16:16:16:16
+
+ChaCha20+Poly1305 RFC 7539 Test Vector #1
+depends_on:MBEDTLS_CHACHAPOLY_C
+auth_crypt_tv:MBEDTLS_CIPHER_CHACHA20_POLY1305:"1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0":"000000000102030405060708":"f33388860000000000004e91":"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":"eead9d67890cbb22392336fea1851f38":"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"
+
+ChaCha20+Poly1305 RFC 7539 Test Vector #1 Unauthentic (1st bit flipped)
+depends_on:MBEDTLS_CHACHAPOLY_C
+auth_crypt_tv:MBEDTLS_CIPHER_CHACHA20_POLY1305:"1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0":"000000000102030405060708":"f33388860000000000004e91":"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":"6ead9d67890cbb22392336fea1851f38":"FAIL"
diff --git a/tests/suites/test_suite_cipher.function b/tests/suites/test_suite_cipher.function
index 92462e5..e4b7e43 100644
--- a/tests/suites/test_suite_cipher.function
+++ b/tests/suites/test_suite_cipher.function
@@ -560,14 +560,14 @@
     int ret;
     unsigned char key[50];
     unsigned char iv[50];
-    unsigned char cipher[200];
-    unsigned char clear[200];
+    unsigned char cipher[265]; /* max size of test data so far */
+    unsigned char clear[265];
+    unsigned char output[267]; /* above + 2 (overwrite check) */
     unsigned char ad[200];
     unsigned char tag[20];
     unsigned char my_tag[20];
     size_t key_len, iv_len, cipher_len, clear_len, ad_len, tag_len;
     mbedtls_cipher_context_t ctx;
-    unsigned char output[200];
     size_t outlen;
 
     mbedtls_cipher_init( &ctx );