diff --git a/packages/core/src/lib/markdown-it/markdown-it-icons.js b/packages/core/src/lib/markdown-it/markdown-it-icons.js
index d2a88e5b29..96dde1dcf2 100644
--- a/packages/core/src/lib/markdown-it/markdown-it-icons.js
+++ b/packages/core/src/lib/markdown-it/markdown-it-icons.js
@@ -10,11 +10,21 @@ module.exports = require('markdown-it-regexp')(
         if (iconFontType === 'glyphicon') {
             return `<span aria-hidden="true" class="glyphicon glyphicon-${iconFontName}"></span>`;
         } else if (iconFontType === 'octicon') {
-            return iconClass ? octicons[iconFontName].toSVG({"class": iconClass})
-                             : octicons[iconFontName].toSVG();
+            // ensure octicons are valid
+            if (!octicons.hasOwnProperty(iconFontName)) {
+                return `<span aria-hidden="true"></span>`;
+            }
+            return iconClass
+                ? octicons[iconFontName].toSVG({"class": iconClass})
+                : octicons[iconFontName].toSVG();
         } else if (iconFontType === 'octiconlight') {
-            return iconClass ? octicons[iconFontName].toSVG({"style": "color: #fff;", "class": iconClass})
-                             : octicons[iconFontName].toSVG({"style": "color: #fff;"});
+            // ensure octicons are valid
+            if (!octicons.hasOwnProperty(iconFontName)) {
+               return `<span aria-hidden="true"></span>`;
+            }
+            return iconClass
+                ? octicons[iconFontName].toSVG({"style": "color: #fff;", "class": iconClass})
+                : octicons[iconFontName].toSVG({"style": "color: #fff;"});
         } else { // If icon is a Font Awesome icon
             return `<span aria-hidden="true" class="${iconFontType} fa-${iconFontName}"></span>`;
         }