diff --git a/tests/suites/test_suite_bignum_mod.function b/tests/suites/test_suite_bignum_mod.function
index 70152845b..eaf2bd5b9 100644
--- a/tests/suites/test_suite_bignum_mod.function
+++ b/tests/suites/test_suite_bignum_mod.function
@@ -737,5 +737,6 @@ exit:
     mbedtls_free(R);
     mbedtls_free(R_COPY);
     mbedtls_free(obuf);
+    mbedtls_free(ref_buf);
 }
 /* END_CASE */