diff --git a/scripts/config.pl b/scripts/config.pl
index cf766a8..619c5ca 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -52,6 +52,7 @@
 #   MBEDTLS_NO_UDBL_DIVISION
 #   MBEDTLS_NO_64BIT_MULTIPLICATION
 #   MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH
+#   MBEDTLS_AES_ONLY_ENCRYPT
 #   and any symbol beginning _ALT
 #
 
@@ -128,6 +129,7 @@
 MBEDTLS_NO_64BIT_MULTIPLICATION
 MBEDTLS_USE_TINYCRYPT
 MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH
+MBEDTLS_AES_ONLY_ENCRYPT
 _ALT\s*$
 );