diff --git a/src/shared/varlink-org.varlink.service.c b/src/shared/varlink-org.varlink.service.c
index 36dc68fd26..e5122c08be 100644
--- a/src/shared/varlink-org.varlink.service.c
+++ b/src/shared/varlink-org.varlink.service.c
@@ -12,7 +12,8 @@ static VARLINK_DEFINE_METHOD(
 
 static VARLINK_DEFINE_METHOD(
                 GetInterfaceDescription,
-                VARLINK_DEFINE_OUTPUT(interface, VARLINK_STRING, 0));
+                VARLINK_DEFINE_INPUT(interface, VARLINK_STRING, 0),
+                VARLINK_DEFINE_OUTPUT(description, VARLINK_STRING, 0));
 
 static VARLINK_DEFINE_ERROR(
                 InterfaceNotFound,