diff --git a/lib/utils.js b/lib/utils.js
index 4f21e7ef1e3..82b2eee568c 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -96,7 +96,9 @@ function acceptParams (str) {
     var splitIndex = str.indexOf('=', index);
     if (splitIndex === -1) break;
 
-    var colonIndex = str.indexOf(';', index);
+    // a parameter value may be a quoted-string, which can itself contain
+    // ";" - so the terminating ";" must not be one inside quotes
+    var colonIndex = indexOfUnquoted(str, ';', index);
     var endIndex = colonIndex === -1 ? length : colonIndex;
 
     if (splitIndex > endIndex) {
@@ -119,6 +121,35 @@ function acceptParams (str) {
   return ret;
 }
 
+/**
+ * Find the index of the first unescaped, unquoted occurrence of `char`
+ * in `str` at or after `fromIndex`, treating a double-quoted substring
+ * (a quoted-string parameter value) as opaque so that `char` occurring
+ * inside it is ignored. Returns -1 if no such occurrence is found.
+ *
+ * @param {String} str
+ * @param {String} char
+ * @param {Number} fromIndex
+ * @return {Number}
+ * @api private
+ */
+
+function indexOfUnquoted(str, char, fromIndex) {
+  var quoted = false;
+
+  for (var i = fromIndex; i < str.length; i++) {
+    var c = str[i];
+
+    if (c === '"' && str[i - 1] !== '\\') {
+      quoted = !quoted;
+    } else if (c === char && !quoted) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
 /**
  * Compile "etag" value to function.
  *
diff --git a/test/utils.js b/test/utils.js
index d1174d014cf..b7856121886 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -43,6 +43,24 @@ describe('utils.normalizeType acceptParams method', () => {
       params: {}
     });
   });
+
+  it('should not split a quoted parameter value on an embedded ";"', () => {
+    const result = utils.normalizeType('text/plain; foo="a;b"; bar=baz');
+    assert.deepEqual(result, {
+      value: 'text/plain',
+      quality: 1,
+      params: { foo: '"a;b"', bar: 'baz' }
+    });
+  });
+
+  it('should not treat an escaped quote inside a parameter value as closing it', () => {
+    const result = utils.normalizeType('text/plain; foo="a\\"b;c"; bar=baz');
+    assert.deepEqual(result, {
+      value: 'text/plain',
+      quality: 1,
+      params: { foo: '"a\\"b;c"', bar: 'baz' }
+    });
+  });
 });
 
 describe('utils.setCharset(type, charset)', function () {