diff --git a/mobile/head_tag.html b/mobile/head_tag.html
index 15d015b..c90b72e 100644
--- a/mobile/head_tag.html
+++ b/mobile/head_tag.html
@@ -67,7 +67,7 @@ api.modifyClass("controller:composer", {
       this.get("toolbarEvent").applySurround("<s>", "</s>", "strikethrough_text");
     },
 	superscript() {
-      this.get("toolbarEvent").applySurround("<sup>", "</sub>", "superscript_text");
+      this.get("toolbarEvent").applySurround("<sup>", "</sup>", "superscript_text");
     },
     subscript() {
       this.get("toolbarEvent").applySurround("<sub>", "</sub>", "subscript_text");