diff --git a/src/driver.h b/src/driver.h
--- a/src/driver.h
+++ b/src/driver.h
@@ -79,7 +79,7 @@ protected:
 		strecpy(buf, GetDriverTypeName(type), lastof(buf));
 		strecpy(buf + 5, name, lastof(buf));
 
-#if !defined(NDEBUG)
+#if !defined(NDEBUG) || defined(WITH_ASSERT)
 		/* NDEBUG disables asserts and gives a warning: unused variable 'P' */
 		std::pair<Drivers::iterator, bool> P =
 #endif /* !NDEBUG */