diff --git a/packages/core/src/inputRules/markInputRule.ts b/packages/core/src/inputRules/markInputRule.ts
index fc1ba923..fa99778b 100644
--- a/packages/core/src/inputRules/markInputRule.ts
+++ b/packages/core/src/inputRules/markInputRule.ts
@@ -26,7 +26,7 @@ export default function (regexp: RegExp, markType: MarkType, getAttrs?: Function
 
     if (match[m]) {
       const matchStart = start + match[0].indexOf(match[m - 1])
-      const matchEnd = matchStart + match[m - 1].length
+      const matchEnd = matchStart + match[m - 1].length - 1
       const textStart = matchStart + match[m - 1].lastIndexOf(match[m])
       const textEnd = textStart + match[m].length