diff --git a/dlib/assert.h b/dlib/assert.h
index 370f9c07a..291b91083 100644
--- a/dlib/assert.h
+++ b/dlib/assert.h
@@ -160,7 +160,7 @@ namespace dlib
 #define DLIBM_CASSERT_1_ARGS(exp)              DLIBM_CASSERT(exp,"")
 #define DLIBM_CASSERT_2_ARGS(exp,message)      DLIBM_CASSERT(exp,message)
 #define DLIBM_GET_3TH_ARG(arg1, arg2, arg3, ...) arg3
-#define DLIBM_CASSERT_CHOOSER(...) DLIB_WORKAROUND_VISUAL_STUDIO_BUGS(DLIBM_GET_3TH_ARG(__VA_ARGS__,  DLIBM_CASSERT_2_ARGS, DLIBM_CASSERT_1_ARGS))
+#define DLIBM_CASSERT_CHOOSER(...) DLIB_WORKAROUND_VISUAL_STUDIO_BUGS(DLIBM_GET_3TH_ARG(__VA_ARGS__,  DLIBM_CASSERT_2_ARGS, DLIBM_CASSERT_1_ARGS, NEVER_USED))
 #define DLIB_CASSERT(...) DLIB_WORKAROUND_VISUAL_STUDIO_BUGS(DLIBM_CASSERT_CHOOSER(__VA_ARGS__)(__VA_ARGS__))