diff --git a/tst/tst.h b/tst/tst.h
index f65571e..8d5fd5e 100644
--- a/tst/tst.h
+++ b/tst/tst.h
@@ -8,6 +8,9 @@
 
 #include <cmocka.h>
 
+// TODO: use cmocka_print_error and remove this proto once cmocka 1.1.7+ is widely available
+void cm_print_error(const char* const format, ...) CMOCKA_PRINTF_ATTRIBUTE(1, 2);
+
 // print log messages, useful when debugging tests
 #define LOG_PRINT false