diff --git a/tests/src/threading_helpers.c b/tests/src/threading_helpers.c
index 5eac029..c1686c2 100644
--- a/tests/src/threading_helpers.c
+++ b/tests/src/threading_helpers.c
@@ -321,8 +321,8 @@
         if (live_mutexes != 0) {
             /* A positive number (more init than free) means that a mutex resource
              * is leaking (on platforms where a mutex consumes more than the
-             * mbedtls_threading_mutex_t object itself). The rare case of a
-             * negative number means a missing init somewhere. */
+             * mbedtls_threading_mutex_t object itself). The (hopefully) rare
+             * case of a negative number means a missing init somewhere. */
             mbedtls_fprintf(stdout, "[mutex: %d leaked] ", live_mutexes);
             live_mutexes = 0;
             mbedtls_test_set_mutex_usage_error("missing free");