diff --git a/tests/AP_gtest.h b/tests/AP_gtest.h
index c7d0734783..2ed1e61ad3 100644
--- a/tests/AP_gtest.h
+++ b/tests/AP_gtest.h
@@ -1,10 +1,14 @@
 /*
  * Utility header for unit tests with gtest.
  */
+
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
 #include <gtest/gtest.h>
 
 
 #define AP_GTEST_PRINTATBLE_PARAM_MEMBER(class_name_, printable_member_) \
+::std::ostream& operator<<(::std::ostream& os, const class_name_& param); \
 ::std::ostream& operator<<(::std::ostream& os, const class_name_& param) \
 { \
     return os << param.printable_member_; \