diff --git a/tests/suites/test_suite_debug.function b/tests/suites/test_suite_debug.function
index 3c77ca5..98f98b0 100644
--- a/tests/suites/test_suite_debug.function
+++ b/tests/suites/test_suite_debug.function
@@ -25,6 +25,11 @@
     *p++ = ':';
     *p++ = ' ';
 
+#if defined(MBEDTLS_THREADING_C)
+    /* Skip "thread ID" (up to the first space) as it is not predictable */
+    while( *str++ != ' ' );
+#endif
+
     memcpy( p, str, strlen( str ) );
     p += strlen( str );