diff --git a/src/lex.js b/src/lex.js
index 87568c4af1..98fa1c0fae 100644
--- a/src/lex.js
+++ b/src/lex.js
@@ -1352,17 +1352,11 @@ Lexer.prototype = {
         sequence = char;
         next = this.peek(index + 1);
         while (reg.nonzeroDigit.test(next) || next === "0") {
-          /* istanbul ignore next */
           index += 1;
-          /* istanbul ignore next */
           char = next;
-          /* istanbul ignore next */
           sequence += char;
-          /* istanbul ignore next */
           body += char;
-          /* istanbul ignore next */
           value += char;
-          /* istanbul ignore next */
           next = this.peek(index + 1);
         }
         groupReferences.push(Number(sequence));
@@ -1471,7 +1465,6 @@ Lexer.prototype = {
       }
 
       if (next === "}") {
-        /* istanbul ignore next */
         return true;
       }
 
diff --git a/tests/unit/parser.js b/tests/unit/parser.js
index 603aea7523..b3fd37b479 100644
--- a/tests/unit/parser.js
+++ b/tests/unit/parser.js
@@ -756,6 +756,16 @@ exports.regexp.uFlag = function (test) {
     .addError(1, 6, "Invalid regular expression.")
     .test("void /.{}/u;", { esversion: 6 });
 
+  TestRun(test)
+    .test([
+      "void /.{0}/;",
+      "void /.{0}/u;",
+      "void /.{9}/;",
+      "void /.{9}/u;",
+      "void /.{23}/;",
+      "void /.{23}/u;"
+    ], { esversion: 6 });
+
   TestRun(test)
     .addError(1, 6, "Invalid regular expression.")
     .test("void /.{,2}/u;", { esversion: 6 });
@@ -768,6 +778,25 @@ exports.regexp.uFlag = function (test) {
     .addError(1, 6, "Invalid regular expression.")
     .test("void /(.)(.)\\3/u;", { esversion: 6 });
 
+  TestRun(test, "Valid group reference - multiple digits")
+    .test([
+      "void /(.)(.)(.)(.)(.)(.)(.)(.)(.)(.)\\10/u;",
+      "void /(.)(.)(.)(.)(.)(.)(.)(.)(.)(.)\\10a/u;",
+      "void /(.)(.)(.)(.)(.)(.)(.)(.)(.)(.)(.)\\11/u;",
+      "void /(.)(.)(.)(.)(.)(.)(.)(.)(.)(.)(.)\\11a/u;"
+    ], { esversion: 6 });
+
+  // A negative syntax test is the only way to verify JSHint is interpeting the
+  // adjacent digits as one reference as opposed to a reference followed by a
+  // literal digit.
+  TestRun(test, "Invalid group reference - two digits")
+    .addError(1, 6, "Invalid regular expression.")
+    .test("void /(.)\\10/u;", { esversion: 6 });
+
+  TestRun(test, "Invalid group reference - three digits")
+    .addError(1, 6, "Invalid regular expression.")
+    .test("void /(.)(.)(.)(.)(.)(.)(.)(.)(.)(.)\\100/u;", { esversion: 6 });
+
   TestRun(test, "Invalid group reference (permitted without flag)")
     .test("void /(.)(.)\\3/;", { esversion: 6 });