diff --git a/src/mbyte.c b/src/mbyte.c
index 545a40d..0443122 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -4799,7 +4799,7 @@
 
     argv[0].v_type = VAR_NUMBER;
     argv[0].vval.v_number = active ? 1 : 0;
-    argv[1].v_type = VAR_NUMBER;
+    argv[1].v_type = VAR_UNKNOWN;
     (void)call_func_retnr(p_imaf, 1, argv, FALSE);
 }