diff --git a/src/fping.c b/src/fping.c
index a6fd668..7905c58 100644
--- a/src/fping.c
+++ b/src/fping.c
@@ -437,6 +437,9 @@ int main(int argc, char** argv)
         { "unreach", 'u', OPTPARSE_NONE },
         { "version", 'v', OPTPARSE_NONE },
         { "reachable", 'x', OPTPARSE_REQUIRED },
+#if defined(DEBUG) || defined(_DEBUG)
+        { NULL, 'z', OPTPARSE_REQUIRED },
+#endif
         { 0, 0, 0 }
     };