diff --git a/common/main.c b/common/main.c
index cc4b50f..8f196a4 100644
--- a/common/main.c
+++ b/common/main.c
@@ -1219,6 +1219,8 @@ static void process_macros (const char *input, char *output)
 
 	if (outputcnt)
 		*output = 0;
+	else
+		*(output - 1) = 0;
 
 #ifdef DEBUG_PARSER
 	printf ("[PROCESS_MACROS] OUTPUT len %d: \"%s\"\n",