diff --git a/.ci/travis-before-install.sh b/.ci/travis-before-install.sh
index 3dd6b8a8..dd624ffa 100755
--- a/.ci/travis-before-install.sh
+++ b/.ci/travis-before-install.sh
@@ -27,7 +27,7 @@ if [[ "${TRAVIS_OS_NAME}" == "linux" && "${BUILD}" == *wheels* ]]; then
         fi
     fi
 
-    sudo service postgresql start ${PGVERSION}
+    sudo pg_ctlcluster ${PGVERSION} main restart
 fi
 
 if [ "${TRAVIS_OS_NAME}" == "osx" ]; then
diff --git a/.travis.yml b/.travis.yml
index be029141..1ace44f9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -138,7 +138,7 @@ matrix:
         # Also use this job to publish the releases and build
         # the documentation.
         - os: linux
-          dist: xenial
+          dist: bionic
           sudo: required
           language: python
           python: "3.6"
diff --git a/asyncpg/__init__.py b/asyncpg/__init__.py
index ee66f932..96b41c89 100644
--- a/asyncpg/__init__.py
+++ b/asyncpg/__init__.py
@@ -31,4 +31,4 @@
 #    snapshots will automatically include the git revision
 #    in __version__, for example: '0.16.0.dev0+ge06ad03'
 
-__version__ = '0.20.0'
+__version__ = '0.20.1'
diff --git a/asyncpg/pgproto b/asyncpg/pgproto
index 484e3520..1b4af3c6 160000
--- a/asyncpg/pgproto
+++ b/asyncpg/pgproto
@@ -1 +1 @@
-Subproject commit 484e3520d8cb0514b7596a8f9eaa80f3f7b79d0c
+Subproject commit 1b4af3c685bfda6c74c082504fe8947c0a55e358
diff --git a/tests/test_codecs.py b/tests/test_codecs.py
index 1299f2bd..abd3c668 100644
--- a/tests/test_codecs.py
+++ b/tests/test_codecs.py
@@ -69,7 +69,6 @@ def _system_timezone():
         decimal.Decimal("-1.00000000000000"),
         decimal.Decimal("-2.00000000000000"),
         decimal.Decimal("1000000000000000.00000000000000"),
-        decimal.Decimal("-0.00000000000000"),
         decimal.Decimal(1234),
         decimal.Decimal(-1234),
         decimal.Decimal("1234000000.00088883231"),
@@ -111,7 +110,7 @@ def _system_timezone():
         decimal.Decimal("0.0"),
         decimal.Decimal("-1.0"),
         decimal.Decimal("1.0E-1000"),
-        decimal.Decimal("1.0E1000"),
+        decimal.Decimal("1E1000"),
         decimal.Decimal("0.000000000000000000000000001"),
         decimal.Decimal("0.000000000000010000000000001"),
         decimal.Decimal("0.00000000000000000000000001"),
@@ -141,6 +140,16 @@ def _system_timezone():
         decimal.Decimal("0.001"),
         decimal.Decimal("0.01"),
         decimal.Decimal("0.1"),
+        decimal.Decimal("0.10"),
+        decimal.Decimal("0.100"),
+        decimal.Decimal("0.1000"),
+        decimal.Decimal("0.10000"),
+        decimal.Decimal("0.100000"),
+        decimal.Decimal("0.00001000"),
+        decimal.Decimal("0.000010000"),
+        decimal.Decimal("0.0000100000"),
+        decimal.Decimal("0.00001000000"),
+        decimal.Decimal("1" + "0" * 117 + "." + "0" * 161)
     )),
     ('bytea', 'bytea', (
         bytes(range(256)),
@@ -502,6 +511,14 @@ async def test_standard_codecs(self):
                     else:
                         self.assertEqual(result, outputval, err_msg)
 
+                    if (typname == 'numeric' and
+                            isinstance(inputval, decimal.Decimal)):
+                        self.assertEqual(
+                            result.as_tuple(),
+                            outputval.as_tuple(),
+                            err_msg,
+                        )
+
             with self.subTest(sample=None, typname=typname):
                 # Test that None is handled for all types.
                 rsample = await st.fetchval(None)