diff --git a/README.md b/README.md
index cd26449..32dc72c 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ by adding `mssqlex` to your list of dependencies in `mix.exs`:
 
 ```elixir
 def deps do
-  [{:mssqlex, "~> 0.1.0"}]
+  [{:mssqlex, "~> 0.1"}]
 end
 ```
 
diff --git a/lib/mssqlex/protocol.ex b/lib/mssqlex/protocol.ex
index 7fedf59..7e186bb 100644
--- a/lib/mssqlex/protocol.ex
+++ b/lib/mssqlex/protocol.ex
@@ -97,7 +97,13 @@ defmodule Mssqlex.Protocol do
     {:ok, result, state}
   | {:error | :disconnect, Exception.t, state}
   def handle_begin(_opts, state) do
-    {:ok, %Result{num_rows: 0}, Map.put(state, :mssql, :transaction)}
+    case state.mssql do
+      :idle -> {:ok, %Result{num_rows: 0}, %{state | mssql: :transaction}}
+      :transaction -> {:error,
+        %Mssqlex.Error{message: "Already in transaction"}}
+      :auto_commit -> {:error,
+        %Mssqlex.Error{message: "Transactions not allowed in autocommit mode"}}
+    end
   end
 
   @doc false
@@ -106,7 +112,7 @@ defmodule Mssqlex.Protocol do
     {:error | :disconnect, Exception.t, state}
   def handle_commit(_opts, state = %{pid: pid}) do
     case ODBC.commit(pid) do
-      :ok -> {:ok, %Result{}, state}
+      :ok -> {:ok, %Result{}, %{state | mssql: :idle}}
       {:error, reason} -> {:error, reason, state}
     end
   end
@@ -117,8 +123,8 @@ defmodule Mssqlex.Protocol do
     {:error | :disconnect, Exception.t, state}
   def handle_rollback(_opts, state = %{pid: pid}) do
     case ODBC.rollback(pid) do
-      :ok -> {:ok, %Result{}, state}
-      {:error, reason} -> {:error, reason. state}
+      :ok -> {:ok, %Result{}, %{state | mssql: :idle}}
+      {:error, reason} -> {:disconnect, reason. state}
     end
   end
 
diff --git a/mix.exs b/mix.exs
index 040b66b..a7ced93 100644
--- a/mix.exs
+++ b/mix.exs
@@ -3,7 +3,7 @@ defmodule Mssqlex.Mixfile do
 
   def project do
     [app: :mssqlex,
-     version: "0.1.0",
+     version: "0.1.1",
      description: "Adapter to Microsoft SQL Server. Using DBConnection and ODBC.",
      elixir: "~> 1.4",
      build_embedded: Mix.env == :prod,