diff --git a/library/ssl_invasive.h b/library/ssl_invasive.h
index 9697a91..f40f0d4 100644
--- a/library/ssl_invasive.h
+++ b/library/ssl_invasive.h
@@ -31,7 +31,8 @@
 #include "common.h"
 #include "mbedtls/md.h"
 
-#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \
+#if defined(MBEDTLS_TEST_HOOKS) &&              \
+    defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \
     ( defined(MBEDTLS_SSL_PROTO_TLS1) ||        \
       defined(MBEDTLS_SSL_PROTO_TLS1_1) |       \
       defined(MBEDTLS_SSL_PROTO_TLS1_2) )
@@ -73,6 +74,6 @@
         const unsigned char *data, size_t data_len_secret,
         size_t min_data_len, size_t max_data_len,
         unsigned char *output );
-#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC && TLS 1.0-1.2 */
+#endif /* MBEDTLS_TEST_HOOKS && MBEDTLS_SSL_SOME_SUITES_USE_CBC && TLS 1.0-1.2 */
 
 #endif /* MBEDTLS_SSL_INVASIVE_H */
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 3c1a01e..d77b658 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -1073,7 +1073,7 @@
 /*
  * Compute HMAC of variable-length data with constant flow.
  */
-int mbedtls_ssl_cf_hmac(
+MBEDTLS_STATIC_TESTABLE int mbedtls_ssl_cf_hmac(
         mbedtls_md_context_t *ctx,
         const unsigned char *add_data, size_t add_data_len,
         const unsigned char *data, size_t data_len_secret,