diff --git a/src/option.c b/src/option.c
index 2347461..d937d02 100644
--- a/src/option.c
+++ b/src/option.c
@@ -8228,7 +8228,8 @@
     {
 # ifdef FEAT_TERMINAL
 	/* Cannot set 'modifiable' when in Terminal mode. */
-	if (term_in_terminal_mode())
+	if (term_in_terminal_mode()
+			 || (bt_terminal(curbuf) && !term_is_finished(curbuf)))
 	{
 	    curbuf->b_p_ma = FALSE;
 	    return (char_u *)N_("E946: Cannot make a terminal with running job modifiable");