diff --git a/lib/onelogin/ruby-saml/utils.rb b/lib/onelogin/ruby-saml/utils.rb
index 7fa8805db..78422d9b8 100644
--- a/lib/onelogin/ruby-saml/utils.rb
+++ b/lib/onelogin/ruby-saml/utils.rb
@@ -22,7 +22,7 @@ class Utils
       #
       def self.format_cert(cert)
         # don't try to format an encoded certificate or if is empty or nil
-        return cert if cert.nil? || cert.empty? || cert.match(/\x0d/)
+        return cert if cert.nil? || cert.empty? || !cert.ascii_only?
 
         if cert.scan(/BEGIN CERTIFICATE/).length > 1
           formatted_cert = []
diff --git a/test/certificates/certificate.der b/test/certificates/certificate.der
new file mode 100644
index 000000000..756d248e2
Binary files /dev/null and b/test/certificates/certificate.der differ
diff --git a/test/utils_test.rb b/test/utils_test.rb
index 18252fa49..b1ccf972d 100644
--- a/test/utils_test.rb
+++ b/test/utils_test.rb
@@ -29,6 +29,11 @@ class UtilsTest < Minitest::Test
       assert_equal formatted_certificate, OneLogin::RubySaml::Utils.format_cert(invalid_certificate2)
     end
 
+    it "returns the cert when it's encoded" do
+      encoded_certificate = read_certificate("certificate.der")
+      assert_equal encoded_certificate, OneLogin::RubySaml::Utils.format_cert(encoded_certificate)
+    end
+
     it "reformats the certificate when there line breaks and no headers" do
       invalid_certificate3 = read_certificate("invalid_certificate3")
       assert_equal formatted_certificate, OneLogin::RubySaml::Utils.format_cert(invalid_certificate3)