diff --git a/tests/suites/main_test.function b/tests/suites/main_test.function
index 8c4ea01..63e91e8 100644
--- a/tests/suites/main_test.function
+++ b/tests/suites/main_test.function
@@ -285,6 +285,10 @@
     mbedtls_memory_buffer_alloc_init( alloc_buf, sizeof(alloc_buf) );
 #endif
 
+#if defined(MBEDTLS_TEST_MUTEX_USAGE)
+    mbedtls_test_mutex_usage_init( );
+#endif
+
     /*
      * The C standard doesn't guarantee that all-bits-0 is the representation
      * of a NULL pointer. We do however use that in our code for initializing