diff --git a/libs/bt/include/psemek/bt/assert.hpp b/libs/bt/include/psemek/bt/assert.hpp
index afea46a1..39cdee4e 100644
--- a/libs/bt/include/psemek/bt/assert.hpp
+++ b/libs/bt/include/psemek/bt/assert.hpp
@@ -25,4 +25,4 @@ namespace psemek::bt
 
 }
 
-#define bt_assert(cond, ...) (void)(!(cond) && ::psemek::bt::assertion_failed("BT assertion failed: ", #cond, " ", ##__VA_ARGS__, " (", __FILE__, ":", __LINE__, ")"))
+#define bt_assert(cond, ...) (void)(!(cond) && ::psemek::bt::assertion_failed("BT assertion failed: ", #cond, " " __VA_OPT__(,) __VA_ARGS__, " (", __FILE__, ":", __LINE__, ")"))