diff --git a/markdown-mode.el b/markdown-mode.el
index 33fee71f..65909aeb 100644
--- a/markdown-mode.el
+++ b/markdown-mode.el
@@ -953,7 +953,7 @@ Compatible with Pandoc, Python Markdown, PHP Markdown Extra, and Leanpub.")
   "Regular expression for Leanpub section markers and related syntax.")
 
 (defconst markdown-regex-sub-superscript
-  "\\(?:^\\|[^\\~^]\\)\\(?1:\\(?2:[~^]\\)\\(?3:[[:alnum:]]+\\)\\(?4:\\2\\)\\)"
+  "\\(?:^\\|[^\\~^]\\)\\(?1:\\(?2:[~^]\\)\\(?3:\\(?:\\\\.\\|[^[:space:]]\\)+?\\)\\(?4:\\2\\)\\)"
   "The regular expression matching a sub- or superscript.
 The leading un-numbered group matches the character before the
 opening tilde or carat, if any, ensuring that it is not a