diff --git a/CHANGELOG.md b/CHANGELOG.md
index dac65691f1318b7fd1540cdb4daa76f72eb2709e..ae93d0963689a246f44c227bd6b8d19cd8a683fa 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,9 @@ This file contains the changes applied to the sources of converse<br>
 The current build version of converse is: `v7.0.3dev`<br>
 If the converse sources have to be updated, apply these changes again, or fix them using plugins
 
+### 2021-04-15
+* Fix an endless loop when parsing bad formatted code block messages
+
 ### 2021-03-25
 * Update retraction warning message in confirm modal
 
diff --git a/src/conversejs/converse.js b/src/conversejs/converse.js
index 802caa42abb208b0cddd5f1d778e7f587a675d56..6140134947b8015c3dd0d3534e2af723dbd73ac9 100644
--- a/src/conversejs/converse.js
+++ b/src/conversejs/converse.js
@@ -91770,7 +91770,7 @@ function getDirectiveLength(d, text, i) {
     return 0;
   } else {
     const substring = text.slice(i + 1);
-    let j;
+    let j = 0;
     let idx = substring.indexOf(d);
 
     while (idx !== -1) {