diff --git a/tests/Makefile b/tests/Makefile
index 85657bde..9fe213e9 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -77,7 +77,7 @@ hello-run: ../examples/ex1.c
 
 libtes%: libtcc_tes%$(EXESUF)
 	@echo ------------ $@ ------------
-	./libtcc_tes$*$(EXESUF) $(TCCFLAGS)
+	./libtcc_tes$*$(EXESUF) $(TCCFLAGS) $(NATIVE_DEFINES)
 
 libtcc_tes%$(EXESUF): libtcc_tes%.c $(LIBTCC)
 	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
diff --git a/tests/libtcc_test_mt.c b/tests/libtcc_test_mt.c
index cebdec36..56294e4c 100644
--- a/tests/libtcc_test_mt.c
+++ b/tests/libtcc_test_mt.c
@@ -102,6 +102,14 @@ void parse_args(TCCState *s)
                 tcc_add_include_path(s, a+2);
             else if (a[1] == 'L')
                 tcc_add_library_path(s, a+2);
+            else if (a[1] == 'D') {
+                char *eq = strchr(a+2, '=');
+                if (eq) {
+                    *eq = 0;
+                    tcc_define_symbol(s, a+2, eq+1);
+                    *eq = '=';
+                }
+            }
         }
     }
 }