diff --git a/tests/suites/test_suite_x509write.data b/tests/suites/test_suite_x509write.data
index 0f19028..f1d4e34 100644
--- a/tests/suites/test_suite_x509write.data
+++ b/tests/suites/test_suite_x509write.data
@@ -265,3 +265,9 @@
 
 Check max serial length
 x509_set_serial_check:
+
+Check max extension length (Max-1)
+x509_set_extension_length_check:0xFFFFFFFE
+
+Check max extension length (Max)
+x509_set_extension_length_check:0xFFFFFFFF
\ No newline at end of file
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index a7ed262..7ec6557 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -750,3 +750,24 @@
     USE_PSA_DONE();
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void x509_set_extension_length_check(int val_len)
+{
+    int ret = 0;
+
+    mbedtls_x509write_csr ctx;
+    mbedtls_x509write_csr_init(&ctx);
+
+    unsigned char buf[EXT_KEY_USAGE_TMP_BUF_MAX_LENGTH] = { 0 };
+    unsigned char *p = buf + sizeof(buf);
+
+    ret = mbedtls_x509_set_extension(&(ctx.MBEDTLS_PRIVATE(extensions)),
+                                     MBEDTLS_OID_EXTENDED_KEY_USAGE,
+                                     MBEDTLS_OID_SIZE(MBEDTLS_OID_EXTENDED_KEY_USAGE),
+                                     0,
+                                     p,
+                                     val_len);
+    TEST_ASSERT(ret == MBEDTLS_ERR_X509_BAD_INPUT_DATA || ret == MBEDTLS_ERR_X509_ALLOC_FAILED);
+}
+/* END_CASE */