diff --git a/language/parse.go b/language/parse.go
index 59b0410..b982d9e 100644
--- a/language/parse.go
+++ b/language/parse.go
@@ -147,6 +147,7 @@
 }
 
 var errInvalidWeight = errors.New("ParseAcceptLanguage: invalid weight")
+var errTagListTooLarge = errors.New("tag list exceeds max length")
 
 // ParseAcceptLanguage parses the contents of an Accept-Language header as
 // defined in http://www.ietf.org/rfc/rfc2616.txt and returns a list of Tags and
@@ -164,6 +165,10 @@
 		}
 	}()
 
+	if strings.Count(s, "-") > 1000 {
+		return nil, nil, errTagListTooLarge
+	}
+
 	var entry string
 	for s != "" {
 		if entry, s = split(s, ','); entry == "" {
diff --git a/language/parse_test.go b/language/parse_test.go
index e1e5653..0eee033 100644
--- a/language/parse_test.go
+++ b/language/parse_test.go
@@ -394,3 +394,16 @@
 		}
 	}
 }
+
+func TestParseAcceptLanguageTooBig(t *testing.T) {
+	s := strings.Repeat("en-x-a-", 333)
+	_, _, err := ParseAcceptLanguage(s)
+	if err != language.ErrSyntax {
+		t.Errorf("ParseAcceptLanguage() unexpected error: got %v, want %v", err, language.ErrSyntax)
+	}
+	s += "en-x-a"
+	_, _, err = ParseAcceptLanguage(s)
+	if err != errTagListTooLarge {
+		t.Errorf("ParseAcceptLanguage() unexpected error: got %v, want %v", err, errTagListTooLarge)
+	}
+}