diff --git a/cmd-set-option.c b/cmd-set-option.c
index 84c12e56..f7e6b730 100644
--- a/cmd-set-option.c
+++ b/cmd-set-option.c
@@ -68,6 +68,7 @@ static enum cmd_retval
 cmd_set_option_exec(struct cmd *self, struct cmdq_item *item)
 {
 	struct args			*args = self->args;
+	int				 append = args_has(args, 'a');
 	struct cmd_find_state		*fs = &item->state.tflag;
 	struct session			*s = fs->s;
 	struct winlink			*wl = fs->wl;
@@ -160,17 +161,6 @@ cmd_set_option_exec(struct cmd *self, struct cmdq_item *item)
 			cmdq_error(item, "not an array: %s", args->argv[0]);
 			return (CMD_RETURN_ERROR);
 		}
-	} else if (*name != '@' && options_array_size(parent, NULL) != -1) {
-		if (value == NULL) {
-			cmdq_error(item, "empty value");
-			return (-1);
-		}
-		if (o == NULL)
-			o = options_empty(oo, options_table_entry(parent));
-		if (!args_has(args, 'a'))
-			options_array_clear(o);
-		options_array_assign(o, value);
-		return (CMD_RETURN_NORMAL);
 	}
 
 	/* With -o, check this option is not already set. */
@@ -204,16 +194,26 @@ cmd_set_option_exec(struct cmd *self, struct cmdq_item *item)
 				options_remove(o);
 		} else
 			options_array_set(o, idx, NULL, 0);
-	} else if (*name == '@')
-		options_set_string(oo, name, args_has(args, 'a'), "%s", value);
-	else if (idx == -1) {
+	} else if (*name == '@') {
+		if (value == NULL) {
+			cmdq_error(item, "empty value");
+			return (CMD_RETURN_ERROR);
+		}
+		options_set_string(oo, name, append, "%s", value);
+	} else if (idx == -1 && options_array_size(parent, NULL) == -1) {
 		error = cmd_set_option_set(self, item, oo, parent, value);
 		if (error != 0)
 			return (CMD_RETURN_ERROR);
 	} else {
+		if (value == NULL) {
+			cmdq_error(item, "empty value");
+			return (CMD_RETURN_ERROR);
+		}
 		if (o == NULL)
 			o = options_empty(oo, options_table_entry(parent));
-		if (options_array_set(o, idx, value, 1) != 0) {
+		if (idx == -1)
+			options_array_assign(o, value);
+		else if (options_array_set(o, idx, value, append) != 0) {
 			cmdq_error(item, "invalid index: %s", args->argv[0]);
 			return (CMD_RETURN_ERROR);
 		}