diff --git a/tests/include/test/ssl_helpers.h b/tests/include/test/ssl_helpers.h
index 72095ea..fecfad9 100644
--- a/tests/include/test/ssl_helpers.h
+++ b/tests/include/test/ssl_helpers.h
@@ -188,7 +188,6 @@
 void mbedtls_test_ssl_buffer_free(mbedtls_test_ssl_buffer *buf);
 
 /*
- *
  * Puts \p input_len bytes from the \p input buffer into the ring buffer \p buf.
  *
  * \p buf must have been initialized and set up by calling
@@ -300,7 +299,6 @@
 /*
  * Callbacks for simulating blocking I/O over connection-oriented transport.
  */
-
 int mbedtls_test_mock_tcp_send_b(void *ctx, const unsigned char *buf,
                                  size_t len);
 
@@ -309,7 +307,6 @@
 /*
  * Callbacks for simulating non-blocking I/O over connection-oriented transport.
  */
-
 int mbedtls_test_mock_tcp_send_nb(void *ctx, const unsigned char *buf,
                                   size_t len);
 
@@ -429,6 +426,21 @@
 
 #endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */
 
+/*
+ * Helper function setting up inverse record transformations
+ * using given cipher, hash, EtM mode, authentication tag length,
+ * and version.
+ */
+#define CHK(x)                                  \
+    do                                          \
+    {                                           \
+        if (!(x))                               \
+        {                                       \
+            ret = -1;                           \
+            goto cleanup;                       \
+        }                                       \
+    } while (0)
+
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
     defined(MBEDTLS_CIPHER_MODE_CBC) && defined(MBEDTLS_AES_C)
 int mbedtls_test_psa_cipher_encrypt_helper(mbedtls_ssl_transform *transform,