diff --git a/src/optionstr.c b/src/optionstr.c
index 47aee35..4c1cacc 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -971,7 +971,7 @@
 	if (gvarp == &p_fenc)
 	{
 	    if (!curbuf->b_p_ma && opt_flags != OPT_GLOBAL)
-		errmsg = e_modifiable;
+		errmsg = e_cannot_make_changes_modifiable_is_off;
 	    else if (vim_strchr(*varp, ',') != NULL)
 		// No comma allowed in 'fileencoding'; catches confusing it
 		// with 'fileencodings'.
@@ -1130,7 +1130,7 @@
     else if (gvarp == &p_ff)
     {
 	if (!curbuf->b_p_ma && !(opt_flags & OPT_GLOBAL))
-	    errmsg = e_modifiable;
+	    errmsg = e_cannot_make_changes_modifiable_is_off;
 	else if (check_opt_strings(*varp, p_ff_values, FALSE) != OK)
 	    errmsg = e_invarg;
 	else