diff --git a/cpp/ql/lib/semmle/code/cpp/regex/internal/ParseRegExp.qll b/cpp/ql/lib/semmle/code/cpp/regex/internal/ParseRegExp.qll
index c30649a2897..430fb88ee48 100644
--- a/cpp/ql/lib/semmle/code/cpp/regex/internal/ParseRegExp.qll
+++ b/cpp/ql/lib/semmle/code/cpp/regex/internal/ParseRegExp.qll
@@ -596,8 +596,6 @@ abstract class RegExp extends StringLiteral {
     or
     this.negativeLookbehindAssertionStart(start, end)
     or
-    this.commentGroupStart(start, end)
-    or
     this.simpleGroupStart(start, end)
   }
 
@@ -674,14 +672,6 @@ abstract class RegExp extends StringLiteral {
     end = start + 4
   }
 
-  /** Matches the start of a comment group, i.e. `(?#`. */
-  private predicate commentGroupStart(int start, int end) {
-    this.isGroupStart(start) and
-    this.getChar(start + 1) = "?" and
-    this.getChar(start + 2) = "#" and
-    end = start + 3
-  }
-
   /** Matches the contents of a group. */
   predicate groupContents(int start, int end, int inStart, int inEnd) {
     this.groupStart(start, inStart) and