diff --git a/src/option.c b/src/option.c
index bfda212..159d1d4 100644
--- a/src/option.c
+++ b/src/option.c
@@ -819,7 +819,8 @@
     if (interface_opt)
       {
 #if defined(SO_BINDTODEVICE)
-	safe_strncpy(interface, interface_opt, IF_NAMESIZE);
+	safe_strncpy(interface, source, IF_NAMESIZE);
+	source = interface_opt;
 #else
 	return _("interface binding not supported");
 #endif