diff --git a/includes/geshi.php b/includes/geshi.php
index 2ee5149..39c4ff0 100644
--- a/includes/geshi.php
+++ b/includes/geshi.php
@@ -2959,6 +2959,7 @@ class GeSHi {
                                 $next_comment_single_pos = $length;
                                 foreach ($this->language_data['COMMENT_SINGLE'] as $comment_key => $comment_mark) {
                                     $match_i = false;
+                                    $case_sensitive_comments = (bool) @$this->language_data['CASE_SENSITIVE'][GESHI_COMMENTS];
                                     if (isset($comment_single_cache_per_key[$comment_key]) &&
                                         ($comment_single_cache_per_key[$comment_key] >= $i ||
                                             $comment_single_cache_per_key[$comment_key] === false)) {
@@ -2970,10 +2971,10 @@ class GeSHi {
                                         $match_i = $comment_single_cache_per_key[$comment_key];
                                     } elseif (
                                         // case sensitive comments
-                                        ($this->language_data['CASE_SENSITIVE'][GESHI_COMMENTS] &&
+                                        ($case_sensitive_comments &&
                                             ($match_i = stripos($part, $comment_mark, $i)) !== false) ||
                                         // non case sensitive
-                                        (!$this->language_data['CASE_SENSITIVE'][GESHI_COMMENTS] &&
+                                        (!$case_sensitive_comments &&
                                             (($match_i = strpos($part, $comment_mark, $i)) !== false))) {
                                         $comment_single_cache_per_key[$comment_key] = $match_i;
                                     } else {