diff --git a/src/encoding/asn1/asn1.go b/src/encoding/asn1/asn1.go
index 2e320897e3..f743cd6f69 100644
--- a/src/encoding/asn1/asn1.go
+++ b/src/encoding/asn1/asn1.go
@@ -365,7 +365,7 @@ func parseUTCTime(bytes []byte) (ret time.Time, err error) {
 // parseGeneralizedTime parses the GeneralizedTime from the given byte slice
 // and returns the resulting time.
 func parseGeneralizedTime(bytes []byte) (ret time.Time, err error) {
-	const formatStr = "20060102150405Z0700"
+	const formatStr = "20060102150405.999999999Z0700"
 	s := string(bytes)
 
 	if ret, err = time.Parse(formatStr, s); err != nil {
diff --git a/src/encoding/asn1/asn1_test.go b/src/encoding/asn1/asn1_test.go
index 90bdfcddf9..0e67dbf396 100644
--- a/src/encoding/asn1/asn1_test.go
+++ b/src/encoding/asn1/asn1_test.go
@@ -323,6 +323,10 @@ func TestUTCTime(t *testing.T) {
 var generalizedTimeTestData = []timeTest{
 	{"20100102030405Z", true, time.Date(2010, 01, 02, 03, 04, 05, 0, time.UTC)},
 	{"20100102030405", false, time.Time{}},
+	{"20100102030405.123456Z", true, time.Date(2010, 01, 02, 03, 04, 05, 123456e3, time.UTC)},
+	{"20100102030405.123456", false, time.Time{}},
+	{"20100102030405.Z", false, time.Time{}},
+	{"20100102030405.", false, time.Time{}},
 	{"20100102030405+0607", true, time.Date(2010, 01, 02, 03, 04, 05, 0, time.FixedZone("", 6*60*60+7*60))},
 	{"20100102030405-0607", true, time.Date(2010, 01, 02, 03, 04, 05, 0, time.FixedZone("", -6*60*60-7*60))},
 	/* These are invalid times. However, the time package normalises times