diff --git a/plugins/base/routes.go b/plugins/base/routes.go
index df32876..c4ab492 100644
--- a/plugins/base/routes.go
+++ b/plugins/base/routes.go
@@ -53,6 +53,7 @@ func registerRoutes(p *alps.GoPlugin) {
 	p.POST("/compose", handleComposeNew)
 
 	p.POST("/compose/attachment", handleComposeAttachment)
+	p.POST("/compose/attachment/:uuid/remove", handleCancelAttachment)
 
 	p.GET("/message/:mbox/:uid/reply", handleReply)
 	p.POST("/message/:mbox/:uid/reply", handleReply)
@@ -763,6 +764,15 @@ func handleComposeAttachment(ctx *alps.Context) error {
 	return ctx.JSON(http.StatusOK, &uuids)
 }
 
+func handleCancelAttachment(ctx *alps.Context) error {
+	uuid := ctx.Param("uuid")
+	a := ctx.Session.PopAttachment(uuid)
+	if a != nil {
+		a.Form.RemoveAll()
+	}
+	return ctx.JSON(http.StatusOK, nil)
+}
+
 func unwrapIMAPAddressList(addrs []*imap.Address) []string {
 	l := make([]string, len(addrs))
 	for i, addr := range addrs {
diff --git a/themes/alps/assets/attachments.js b/themes/alps/assets/attachments.js
index 612808a..dc6cc04 100644
--- a/themes/alps/assets/attachments.js
+++ b/themes/alps/assets/attachments.js
@@ -80,6 +80,12 @@ function attachFile(file) {
 		attachments = attachments.filter(a => a !== attachment);
 		node.remove();
 		updateState();
+
+		if (typeof attachment.uuid !== "undefined") {
+			const cancel = new XMLHttpRequest();
+			cancel.open("POST", `/compose/attachment/${attachment.uuid}/remove`);
+			cancel.send();
+		}
 	});
 
 	let formData = new FormData();