diff --git a/plugins/show-invisibles/prism-show-invisibles.js b/plugins/show-invisibles/prism-show-invisibles.js
index 72833fa949..f3d120a9e8 100644
--- a/plugins/show-invisibles/prism-show-invisibles.js
+++ b/plugins/show-invisibles/prism-show-invisibles.js
@@ -10,6 +10,8 @@ if (
 Prism.hooks.add('before-highlight', function(env) {
 	var tokens = env.grammar;
 
+	if (!tokens) return;
+
 	tokens.tab = /\t/g;
 	tokens.crlf = /\r\n/g;
 	tokens.lf = /\n/g;
diff --git a/plugins/show-invisibles/prism-show-invisibles.min.js b/plugins/show-invisibles/prism-show-invisibles.min.js
index a8562ec977..9df7258c89 100644
--- a/plugins/show-invisibles/prism-show-invisibles.min.js
+++ b/plugins/show-invisibles/prism-show-invisibles.min.js
@@ -1 +1 @@
-!function(){"undefined"!=typeof self&&!self.Prism||"undefined"!=typeof global&&!global.Prism||Prism.hooks.add("before-highlight",function(e){var f=e.grammar;f.tab=/\t/g,f.crlf=/\r\n/g,f.lf=/\n/g,f.cr=/\r/g,f.space=/ /g})}();
\ No newline at end of file
+!function(){"undefined"!=typeof self&&!self.Prism||"undefined"!=typeof global&&!global.Prism||Prism.hooks.add("before-highlight",function(e){var f=e.grammar;f&&(f.tab=/\t/g,f.crlf=/\r\n/g,f.lf=/\n/g,f.cr=/\r/g,f.space=/ /g)})}();
\ No newline at end of file