diff --git a/test/test.h b/test/test.h
index 0815cfcfa..987e361bf 100644
--- a/test/test.h
+++ b/test/test.h
@@ -84,8 +84,8 @@ extern "C" {
 #endif
   msg_t TestThread(void *p);
   void test_printn(uint32_t n);
-  void test_print(char *msgp);
-  void test_println(char *msgp);
+  void test_print(const char *msgp);
+  void test_println(const char *msgp);
   void test_emit_token(char token);
   bool_t _test_fail(unsigned point);
   bool_t _test_assert(unsigned point, bool_t condition);