diff --git a/examples/unity_config.h b/examples/unity_config.h
index c79dd5a90..41195c2bd 100644
--- a/examples/unity_config.h
+++ b/examples/unity_config.h
@@ -228,8 +228,10 @@
 /* #define UNITY_OUTPUT_CHAR_HEADER_DECLARATION    RS232_putc(int) */
 /* #define UNITY_OUTPUT_FLUSH()                    RS232_flush() */
 /* #define UNITY_OUTPUT_FLUSH_HEADER_DECLARATION   RS232_flush(void) */
-/* #define UNITY_OUTPUT_START()                    RS232_config(115200,1,8,0) */
-/* #define UNITY_OUTPUT_COMPLETE()                 RS232_close() */
+/* #define UNITY_OUTPUT_START()                       RS232_config(115200,1,8,0) */
+/* #define UNITY_OUTPUT_START_HEADER_DECLARATION       RS232_config(int,int,int,int) */
+/* #define UNITY_OUTPUT_COMPLETE()                    RS232_close() */
+/* #define UNITY_OUTPUT_COMPLETE_HEADER_DECLARATION    RS232_close(void) */
 
 /* Some compilers require a custom attribute to be assigned to pointers, like
  * `near` or `far`. In these cases, you can give Unity a safe default for these
diff --git a/src/unity_internals.h b/src/unity_internals.h
index e8a26ad22..a39c5a52e 100644
--- a/src/unity_internals.h
+++ b/src/unity_internals.h
@@ -363,10 +363,20 @@ typedef UNITY_FLOAT_TYPE UNITY_FLOAT;
 
 #ifndef UNITY_OUTPUT_START
 #define UNITY_OUTPUT_START()
+#else
+  /* If defined as something else, make sure we declare it here so it's ready for use */
+  #ifdef UNITY_OUTPUT_START_HEADER_DECLARATION
+    extern void UNITY_OUTPUT_START_HEADER_DECLARATION;
+  #endif
 #endif
 
 #ifndef UNITY_OUTPUT_COMPLETE
 #define UNITY_OUTPUT_COMPLETE()
+#else
+  /* If defined as something else, make sure we declare it here so it's ready for use */
+  #ifdef UNITY_OUTPUT_COMPLETE_HEADER_DECLARATION
+    extern void UNITY_OUTPUT_COMPLETE_HEADER_DECLARATION;
+  #endif
 #endif
 
 #ifdef UNITY_INCLUDE_EXEC_TIME