diff --git a/src/beast/modules/beast_core/diagnostic/UnitTest.cpp b/src/beast/modules/beast_core/diagnostic/UnitTest.cpp
index 77b2b0aa93..5a566523da 100644
--- a/src/beast/modules/beast_core/diagnostic/UnitTest.cpp
+++ b/src/beast/modules/beast_core/diagnostic/UnitTest.cpp
@@ -56,6 +56,7 @@ String const& UnitTest::getPackageName() const noexcept
 
 Journal UnitTest::journal () const
 {
+    bassert (m_runner != nullptr);
     return m_runner->journal();
 }