diff --git a/gpssim.c b/gpssim.c
index b205234..8766cb3 100644
--- a/gpssim.c
+++ b/gpssim.c
@@ -1791,7 +1791,7 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
-	while ((result=getopt(argc,argv,"e:u:g:c:l:o:s:b:T:t:d:iv"))!=-1)
+	while ((result=getopt(argc,argv,"e:u:x:g:c:l:o:s:b:T:t:d:iv"))!=-1)
 	{
 		switch (result)
 		{