diff --git a/test/Makefile b/test/Makefile
index 03b59bc4c3cd9a41109d2fc8512c3e60c19dbcf9..9de7a49ac3b316d2778f1111b28780996b08cdcc 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -14,6 +14,7 @@ CFLAGS += -Wbad-function-cast -Wcast-qual -Wold-style-definition -Wshadow -Wstri
 #DEBUG = -O0 -g
 CFLAGS += $(DEBUG)
 DEFINES =  -D UNITY_OUTPUT_CHAR=putcharSpy
+DEFINES += -D UNITY_OUTPUT_CHAR_HEADER_DECLARATION=putcharSpy\(int\)
 DEFINES += -D UNITY_SUPPORT_64 -D UNITY_INCLUDE_DOUBLE
 SRC = ../src/unity.c tests/testunity.c build/testunityRunner.c
 INC_DIR = -I ../src