diff --git a/postgresql-simple-queue.cabal b/postgresql-simple-queue.cabal
--- a/postgresql-simple-queue.cabal
+++ b/postgresql-simple-queue.cabal
@@ -1,9 +1,11 @@
--- This file has been generated from package.yaml by hpack version 0.17.1.
+-- This file has been generated from package.yaml by hpack version 0.20.0.
 --
 -- see: https://github.com/sol/hpack
+--
+-- hash: 54ecbff1eaa2b7aadf2870516b4db0aeb56c9671f79120584006de5903dbff75
 
 name:           postgresql-simple-queue
-version:        1.0.0
+version:        1.0.1
 synopsis:       A PostgreSQL backed queue
 description:    This module utilize PostgreSQL to implement a durable queue for efficently processing arbitrary payloads which can be represented as JSON.
                 .
@@ -31,14 +33,14 @@
                 >
                 > To support multiple queues in the same database, the API expects a table name string
                 > to determine which queue tables to use.
+category:       Web
 homepage:       https://github.com/jfischoff/postgresql-queue#readme
 bug-reports:    https://github.com/jfischoff/postgresql-queue/issues
-license:        BSD3
-license-file:   LICENSE
 author:         Jonathan Fischoff
 maintainer:     jonathangfischoff@gmail.com
 copyright:      2017 Jonathan Fischoff
-category:       Web
+license:        BSD3
+license-file:   LICENSE
 build-type:     Simple
 cabal-version:  >= 1.10
 
@@ -52,53 +54,54 @@
 library
   hs-source-dirs:
       src
+  ghc-options: -Wall -Wno-unused-do-bind
+  build-depends:
+      aeson
+    , base >=4.7 && <5
+    , bytestring
+    , exceptions
+    , monad-control
+    , pg-transact
+    , postgresql-simple
+    , random
+    , stm
+    , text
+    , time
+    , transformers
   exposed-modules:
       Database.PostgreSQL.Simple.Queue
       Database.PostgreSQL.Simple.Queue.Migrate
   other-modules:
       Paths_postgresql_simple_queue
-  build-depends:
-      base >=4.7 && <5
-    , time
-    , transformers
-    , random
-    , text
-    , monad-control
-    , exceptions
-    , postgresql-simple
-    , pg-transact
-    , aeson
-    , bytestring
-    , stm
   default-language: Haskell2010
-  ghc-options: -Wall -Wno-unused-do-bind
 
 test-suite unit-tests
   type: exitcode-stdio-1.0
+  main-is: Spec.hs
   hs-source-dirs:
       test
-  main-is: Spec.hs
-  other-modules:
-      Database.PostgreSQL.Simple.QueueSpec
+  ghc-options: -Wall -Wno-unused-do-bind -O2 -threaded -rtsopts -with-rtsopts=-N
   build-depends:
-      base >=4.7 && <5
-    , time
-    , transformers
-    , random
-    , text
-    , monad-control
-    , exceptions
-    , postgresql-simple
-    , pg-transact
-    , aeson
+      aeson
+    , async
+    , base >=4.7 && <5
     , bytestring
-    , stm
-    , postgresql-simple-queue
+    , exceptions
     , hspec
     , hspec-discover
     , hspec-expectations-lifted
     , hspec-pg-transact
-    , async
+    , monad-control
+    , pg-transact
+    , postgresql-simple
+    , postgresql-simple-queue
+    , random
     , split
-  ghc-options: -Wall -Wno-unused-do-bind -O2 -threaded -rtsopts -with-rtsopts=-N
+    , stm
+    , text
+    , time
+    , transformers
+  other-modules:
+      Database.PostgreSQL.Simple.QueueSpec
+      Paths_postgresql_simple_queue
   default-language: Haskell2010
diff --git a/src/Database/PostgreSQL/Simple/Queue/Migrate.hs b/src/Database/PostgreSQL/Simple/Queue/Migrate.hs
--- a/src/Database/PostgreSQL/Simple/Queue/Migrate.hs
+++ b/src/Database/PostgreSQL/Simple/Queue/Migrate.hs
@@ -43,7 +43,12 @@
   "CREATE SCHEMA IF NOT EXISTS " <> fromString schemaName <> ";" <>
   "SET search_path TO " <> fromString schemaName <> ";" <> [sql|
 
-  CREATE TYPE state_t AS ENUM ('enqueued', 'dequeued');
+  DO $$
+  BEGIN
+    IF NOT EXISTS (SELECT 1 FROM pg_type WHERE typname = 'state_t') THEN
+      CREATE TYPE state_t AS ENUM ('enqueued', 'dequeued');
+    END IF;
+  END$$;
 
   CREATE OR REPLACE FUNCTION update_row_modified_function()
   RETURNS TRIGGER AS
@@ -55,7 +60,7 @@
   $$
   language 'plpgsql';
 
-  CREATE TABLE payloads
+  CREATE TABLE IF NOT EXISTS payloads
   ( id BIGSERIAL PRIMARY KEY
   , value jsonb NOT NULL
   , attempts int NOT NULL DEFAULT 0
@@ -64,9 +69,10 @@
   , modified_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT clock_timestamp()
   );
 
-  CREATE INDEX active_created_at_idx ON payloads (created_at)
+  CREATE INDEX IF NOT EXISTS active_created_at_idx ON payloads (created_at)
     WHERE (state = 'enqueued');
 
+  DROP TRIGGER IF EXISTS payloads_modified ON payloads;
   CREATE TRIGGER payloads_modified
   BEFORE UPDATE ON payloads
   FOR EACH ROW EXECUTE PROCEDURE update_row_modified_function();
diff --git a/test/Database/PostgreSQL/Simple/QueueSpec.hs b/test/Database/PostgreSQL/Simple/QueueSpec.hs
--- a/test/Database/PostgreSQL/Simple/QueueSpec.hs
+++ b/test/Database/PostgreSQL/Simple/QueueSpec.hs
@@ -10,6 +10,7 @@
 import           Data.List
 import           Database.PostgreSQL.Simple.Queue
 import           Database.PostgreSQL.Simple.Queue.Migrate
+import           Database.PostgreSQL.Transact (getConnection)
 import           Test.Hspec                     (Spec, hspec, it)
 import           Test.Hspec.Expectations.Lifted
 import           Test.Hspec.DB
@@ -27,6 +28,11 @@
 
 spec :: Spec
 spec = describeDB (migrate schemaName) "Database.Queue" $ do
+
+  it "is okay to migrate multiple times" $ \db -> runDB db $ do
+      conn <- getConnection
+      replicateM_ 2 $ liftIO $ migrate schemaName conn
+
   itDB "empty locks nothing" $
     (either throwM return =<< (withPayloadDB schemaName 8 return))
       `shouldReturn` Nothing