diff --git a/src/README.md b/src/README.md
index 31386d9..3196ef7 100644
--- a/src/README.md
+++ b/src/README.md
@@ -11,7 +11,9 @@ SSH credentials, and more.
 ## About the Charm
 
 This charm installs Vault from the Ubuntu Snap Store and
-supports the PostgreSQL storage backend only.
+supports the PostgreSQL and MySQL storage backends. Note that Vault itself
+does not support PostgreSQL 10, so neither does this charm. If you're
+deploying on bionic, you'll need to deploy a 9.x version of PostgreSQL.
 
 After deploying and relating the charm to postgresql, install
 the vault snap locally and use "vault init" to create the
diff --git a/src/metadata.yaml b/src/metadata.yaml
index cb6be16..f09c31f 100644
--- a/src/metadata.yaml
+++ b/src/metadata.yaml
@@ -12,8 +12,8 @@ description: |
   credentials, SQL/NoSQL databases, X.509 certificates,
   SSH credentials, and more.
 series:
-  - bionic
   - xenial
+  - bionic
 tags:
   - security
 requires:
diff --git a/src/reactive/vault.py b/src/reactive/vault.py
index 349326d..380af92 100644
--- a/src/reactive/vault.py
+++ b/src/reactive/vault.py
@@ -212,7 +212,7 @@ def mysql_setup(database):
 @when_not('vault.schema.created')
 def create_vault_table(pgsql):
     status_set('maintenance', 'connecting to database')
-    conn = psycopg2.connect(pgsql.master)
+    conn = psycopg2.connect(str(pgsql.master))
     cur = conn.cursor()
     status_set('maintenance', 'creating vault table')
     cur.execute(VAULT_TABLE_DDL)
diff --git a/src/tests/bundles/bionic-postgres.yaml b/src/tests/bundles/bionic-postgres.yaml
new file mode 100644
index 0000000..75c1699
--- /dev/null
+++ b/src/tests/bundles/bionic-postgres.yaml
@@ -0,0 +1,13 @@
+series: bionic
+services:
+  vault:
+    num_units: 1
+    series: bionic
+    charm: ../../../vault
+  postgresql:
+    series: xenial
+    charm: cs:postgresql
+    num_units: 1
+relations:
+- - vault:db
+  - postgresql:db
diff --git a/src/tests/tests.yaml b/src/tests/tests.yaml
index b5b20b1..f139d58 100644
--- a/src/tests/tests.yaml
+++ b/src/tests/tests.yaml
@@ -7,6 +7,7 @@ gate_bundles:
   - xenial-ha-mysql
   - xenial-postgres
   - xenial-mysql
+  - bionic-postgres
 smoke_bundles:
   - xenial-mysql
 dev_bundles: