diff --git a/scripts/config.pl b/scripts/config.pl
index 006a58d..38fa97c 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -128,6 +128,7 @@
 MBEDTLS_REMOVE_ARC4_CIPHERSUITES
 MBEDTLS_RSA_NO_CRT
 MBEDTLS_SSL_HW_RECORD_ACCEL
+MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN
 MBEDTLS_TEST_NULL_ENTROPY
 MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION
 MBEDTLS_ZLIB_SUPPORT