diff --git a/Changelog.md b/Changelog.md
index 254c44bc..4065dd5d 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -4,12 +4,25 @@
 
 Breaking
 
+* Encoding of `x509::Time` values changed since in some cases it needs to
+  encode as either UTCTime or GeneralizedTime depending on the year. Thus,
+  there is no simple `encode` method anymore but rather, there now is
+  `encode_utc_time`, `encode_generalized_time`, or `encode_varied` to make
+  the choice explicit. [(#84)]
+
 New
 
 Bug Fixes
 
+* Stop refusing to make IPv6-only ROAs (this wasn’t on purpose, honest).
+  [(#82)]
+* Empty `IpBlocks` and `AsBlocks` where equal to everything. [(#83)]
+
 Dependencies
 
+[(#82)]: https://github.com/NLnetLabs/rpki-rs/pull/82
+[(#83)]: https://github.com/NLnetLabs/rpki-rs/pull/83
+[(#84)]: https://github.com/NLnetLabs/rpki-rs/pull/84
 
 
 # 0.7.0
diff --git a/src/crl.rs b/src/crl.rs
index 08aae277..dddd1ddc 100644
--- a/src/crl.rs
+++ b/src/crl.rs
@@ -423,8 +423,8 @@ impl TbsCertList<RevokedCertificates> {
             1.encode(), // version
             self.signature.x509_encode(),
             self.issuer.encode_ref(),
-            self.this_update.encode(),
-            self.next_update.encode(),
+            self.this_update.encode_varied(),
+            self.next_update.encode_varied(),
             self.revoked_certs.encode_ref(),
             encode::sequence_as(Tag::CTX_0, 
                 encode::sequence((
@@ -597,7 +597,7 @@ impl CrlEntry {
     pub fn encode(self) -> impl encode::Values {
         encode::sequence((
             self.user_certificate.encode(),
-            self.revocation_date.encode(),
+            self.revocation_date.encode_varied(),
         ))
     }
 }
diff --git a/src/manifest.rs b/src/manifest.rs
index 4a1aa073..a39fce4d 100644
--- a/src/manifest.rs
+++ b/src/manifest.rs
@@ -343,8 +343,8 @@ impl ManifestContent {
     pub fn encode_ref<'a>(&'a self) -> impl encode::Values + 'a {
         encode::sequence((
             self.manifest_number.encode(),
-            self.this_update.encode(),
-            self.next_update.encode(),
+            self.this_update.encode_generalized_time(),
+            self.next_update.encode_generalized_time(),
             self.file_hash_alg.encode_oid(),
             encode::sequence(
                 &self.file_list
diff --git a/src/sigobj.rs b/src/sigobj.rs
index faa0aef2..5abb0f3a 100644
--- a/src/sigobj.rs
+++ b/src/sigobj.rs
@@ -307,7 +307,7 @@ impl SignedAttrs {
                 encode::sequence((
                     oid::SIGNING_TIME.encode(),
                     encode::set(
-                        time.encode(),
+                        time.encode_varied(),
                     )
                 ))
             }),
diff --git a/src/x509.rs b/src/x509.rs
index dc4a08ba..3e643325 100644
--- a/src/x509.rs
+++ b/src/x509.rs
@@ -683,6 +683,23 @@ impl Time {
             Ok(())
         }
     }
+
+    pub fn encode_utc_time(self) -> impl encode::Values {
+        UtcTime(self).encode()
+    }
+
+    pub fn encode_generalized_time(self) -> impl encode::Values {
+        GeneralizedTime(self).encode()
+    }
+
+    pub fn encode_varied(self) -> impl encode::Values {
+        if self.year() < 1950 || self.year() > 2049 {
+            (None, Some(self.encode_generalized_time()))
+        }
+        else {
+            (Some(self.encode_utc_time()), None)
+        }
+    }
 }
 
 
@@ -794,9 +811,34 @@ fn read_four_char<S: decode::Source>(source: &mut S) -> Result<u32, S::Err> {
 }
 
 
-//--- PrimitiveContent
+//------------ AsUtcTime -----------------------------------------------------
+
+pub struct UtcTime(Time);
+
+impl PrimitiveContent for UtcTime {
+    const TAG: Tag = Tag::UTC_TIME;
+
+    fn encoded_len(&self, _: Mode) -> usize {
+        13 // yyMMddhhmmssZ
+    }
+
+    fn write_encoded<W: io::Write>(
+        &self, _: Mode, target: &mut W
+    ) -> Result<(), io::Error> {
+        write!(
+            target, "{:02}{:02}{:02}{:02}{:02}{:02}Z",
+            self.0.year() % 100, self.0.month(), self.0.day(),
+            self.0.hour(), self.0.minute(), self.0.second()
+        )
+    }
+}
+
+
+//------------ AsGeneralizedTime ---------------------------------------------
+
+pub struct GeneralizedTime(Time);
 
-impl PrimitiveContent for Time {
+impl PrimitiveContent for GeneralizedTime {
     const TAG: Tag = Tag::GENERALIZED_TIME;
 
     fn encoded_len(&self, _: Mode) -> usize {
@@ -881,8 +923,8 @@ impl Validity {
 
     pub fn encode(self) -> impl encode::Values {
         encode::sequence((
-            self.not_before.encode(),
-            self.not_after.encode(),
+            self.not_before.encode_varied(),
+            self.not_after.encode_varied(),
         ))
     }
 }