diff --git a/source/mijin/logging/stdio_sink.hpp b/source/mijin/logging/stdio_sink.hpp
index 1a76b86..7aa1e8c 100644
--- a/source/mijin/logging/stdio_sink.hpp
+++ b/source/mijin/logging/stdio_sink.hpp
@@ -56,6 +56,7 @@ public:
         {
             static_assert(always_false_v<char_t>, "Character type not supported.");
         }
+        std::fflush(stream);
     }
 };