diff --git a/spec/custom_drivers_types_spec.cr b/spec/custom_drivers_types_spec.cr
new file mode 100644
index 0000000..2929d0f
--- /dev/null
+++ b/spec/custom_drivers_types_spec.cr
@@ -0,0 +1,299 @@
+require "./spec_helper"
+
+module GenericResultSet
+  @index = 0
+
+  def move_next
+    @index = 0
+    true
+  end
+
+  def column_count : Int32
+    @row.size
+  end
+
+  def column_name(index : Int32) : String
+    index.to_s
+  end
+
+  def column_type(index : Int32)
+    @row[index].class
+  end
+
+  {% for t in DB::TYPES %}
+    # Reads the next column as a nillable {{t}}.
+    def read?(t : {{t}}.class) : {{t}}?
+      read_and_move_next_column as {{t}}?
+    end
+  {% end %}
+
+  def read_and_move_next_column
+    @index += 1
+    @row[@index - 1]
+  end
+end
+
+class FooValue
+  def initialize(@value : Int32)
+  end
+
+  def value
+    @value
+  end
+end
+
+class FooDriver < DB::Driver
+  alias Any = DB::Any | FooValue
+  @@row = [] of Any
+
+  def self.fake_row=(row : Array(Any))
+    @@row = row
+  end
+
+  def self.fake_row
+    @@row
+  end
+
+  def build_connection(db : DB::Database) : DB::Connection
+    FooConnection.new(db)
+  end
+
+  class FooConnection < DB::Connection
+    def build_statement(query)
+      FooStatement.new(self)
+    end
+  end
+
+  class FooStatement < DB::Statement
+    protected def perform_query(args : Enumerable) : DB::ResultSet
+      args.each { |arg| process_arg arg }
+      FooResultSet.new(self, FooDriver.fake_row)
+    end
+
+    protected def perform_exec(args : Enumerable) : DB::ExecResult
+      args.each { |arg| process_arg arg }
+      DB::ExecResult.new 0i64, 0i64
+    end
+
+    private def process_arg(value : FooDriver::Any)
+    end
+
+    private def process_arg(value)
+      raise "#{self.class} does not support #{value.class} params"
+    end
+  end
+
+  class FooResultSet < DB::ResultSet
+    include GenericResultSet
+
+    def initialize(statement, @row : Array(FooDriver::Any))
+      super(statement)
+    end
+
+    def read?(t : FooValue.class) : FooValue?
+      read_and_move_next_column.as(FooValue?)
+    end
+  end
+end
+
+DB.register_driver "foo", FooDriver
+
+class BarValue
+  getter value
+
+  def initialize(@value : Int32)
+  end
+end
+
+class BarDriver < DB::Driver
+  alias Any = DB::Any | BarValue
+  @@row = [] of Any
+
+  def self.fake_row=(row : Array(Any))
+    @@row = row
+  end
+
+  def self.fake_row
+    @@row
+  end
+
+  def build_connection(db : DB::Database) : DB::Connection
+    BarConnection.new(db)
+  end
+
+  class BarConnection < DB::Connection
+    def build_statement(query)
+      BarStatement.new(self)
+    end
+  end
+
+  class BarStatement < DB::Statement
+    protected def perform_query(args : Enumerable) : DB::ResultSet
+      args.each { |arg| process_arg arg }
+      BarResultSet.new(self, BarDriver.fake_row)
+    end
+
+    protected def perform_exec(args : Enumerable) : DB::ExecResult
+      args.each { |arg| process_arg arg }
+      DB::ExecResult.new 0i64, 0i64
+    end
+
+    private def process_arg(value : BarDriver::Any)
+    end
+
+    private def process_arg(value)
+      raise "#{self.class} does not support #{value.class} params"
+    end
+  end
+
+  class BarResultSet < DB::ResultSet
+    include GenericResultSet
+
+    def initialize(statement, @row : Array(BarDriver::Any))
+      super(statement)
+    end
+
+    def read?(t : BarValue.class) : BarValue?
+      read_and_move_next_column.as(BarValue?)
+    end
+  end
+end
+
+DB.register_driver "bar", BarDriver
+
+describe DB do
+  it "should be able to register multiple drivers" do
+    DB.open("foo://host").driver.should be_a(FooDriver)
+    DB.open("bar://host").driver.should be_a(BarDriver)
+  end
+
+  it "Foo and Bar drivers should return fake_row" do
+    with_witness do |w|
+      DB.open("foo://host") do |db|
+        # TODO somehow FooValue.new(99) is needed otherwise the read_object assertion fail
+        FooDriver.fake_row = [1, "string", FooValue.new(3), FooValue.new(99)] of FooDriver::Any
+        db.query "query" do |rs|
+          w.check
+          rs.move_next
+          rs.read?(Int32).should eq(1)
+          rs.read?(String).should eq("string")
+          rs.read(FooValue).value.should eq(3)
+        end
+      end
+    end
+
+    with_witness do |w|
+      DB.open("bar://host") do |db|
+        # TODO somehow BarValue.new(99) is needed otherwise the read_object assertion fail
+        BarDriver.fake_row = [BarValue.new(4), "lorem", 1.0, BarValue.new(99)] of BarDriver::Any
+        db.query "query" do |rs|
+          w.check
+          rs.move_next
+          rs.read(BarValue).value.should eq(4)
+          rs.read?(String).should eq("lorem")
+          rs.read?(Float64).should eq(1.0)
+        end
+      end
+    end
+  end
+
+  it "Foo and Bar drivers should not implement each other read" do
+    with_witness do |w|
+      DB.open("foo://host") do |db|
+        FooDriver.fake_row = [1] of FooDriver::Any
+        db.query "query" do |rs|
+          rs.move_next
+          expect_raises Exception, "read?(t : BarValue) is not implemented in FooDriver::FooResultSet" do
+            w.check
+            rs.read(BarValue)
+          end
+        end
+      end
+    end
+
+    with_witness do |w|
+      DB.open("bar://host") do |db|
+        BarDriver.fake_row = [1] of BarDriver::Any
+        db.query "query" do |rs|
+          rs.move_next
+          expect_raises Exception, "read?(t : FooValue) is not implemented in BarDriver::BarResultSet" do
+            w.check
+            rs.read(FooValue)
+          end
+        end
+      end
+    end
+  end
+
+  it "allow custom types to be used as arguments for query" do
+    DB.open("foo://host") do |db|
+      FooDriver.fake_row = [1, "string"] of FooDriver::Any
+      db.query "query" { }
+      db.query "query", 1 { }
+      db.query "query", 1, "string" { }
+      db.query("query", Bytes.new(4)) { }
+      db.query("query", 1, "string", FooValue.new(5)) { }
+      db.query "query", [1, "string", FooValue.new(5)] { }
+
+      db.query("query").close
+      db.query("query", 1).close
+      db.query("query", 1, "string").close
+      db.query("query", Bytes.new(4)).close
+      db.query("query", 1, "string", FooValue.new(5)).close
+      db.query("query", [1, "string", FooValue.new(5)]).close
+    end
+
+    DB.open("bar://host") do |db|
+      BarDriver.fake_row = [1, "string"] of BarDriver::Any
+      db.query "query" { }
+      db.query "query", 1 { }
+      db.query "query", 1, "string" { }
+      db.query("query", Bytes.new(4)) { }
+      db.query("query", 1, "string", BarValue.new(5)) { }
+      db.query "query", [1, "string", BarValue.new(5)] { }
+
+      db.query("query").close
+      db.query("query", 1).close
+      db.query("query", 1, "string").close
+      db.query("query", Bytes.new(4)).close
+      db.query("query", 1, "string", BarValue.new(5)).close
+      db.query("query", [1, "string", BarValue.new(5)]).close
+    end
+  end
+
+  it "allow custom types to be used as arguments for exec" do
+    DB.open("foo://host") do |db|
+      FooDriver.fake_row = [1, "string"] of FooDriver::Any
+      db.exec("query")
+      db.exec("query", 1)
+      db.exec("query", 1, "string")
+      db.exec("query", Bytes.new(4))
+      db.exec("query", 1, "string", FooValue.new(5))
+      db.exec("query", [1, "string", FooValue.new(5)])
+    end
+
+    DB.open("bar://host") do |db|
+      BarDriver.fake_row = [1, "string"] of BarDriver::Any
+      db.exec("query")
+      db.exec("query", 1)
+      db.exec("query", 1, "string")
+      db.exec("query", Bytes.new(4))
+      db.exec("query", 1, "string", BarValue.new(5))
+      db.exec("query", [1, "string", BarValue.new(5)])
+    end
+  end
+
+  it "Foo and Bar drivers should not implement each other params" do
+    DB.open("foo://host") do |db|
+      expect_raises Exception, "FooDriver::FooStatement does not support BarValue params" do
+        db.exec("query", [BarValue.new(5)])
+      end
+    end
+
+    DB.open("bar://host") do |db|
+      expect_raises Exception, "BarDriver::BarStatement does not support FooValue params" do
+        db.exec("query", [FooValue.new(5)])
+      end
+    end
+  end
+end
diff --git a/spec/dummy_driver.cr b/spec/dummy_driver.cr
index b57e5d4..9933604 100644
--- a/spec/dummy_driver.cr
+++ b/spec/dummy_driver.cr
@@ -42,23 +42,31 @@ class DummyDriver < DB::Driver
       super(connection)
     end
 
-    protected def perform_query(args : Slice(DB::Any))
+    protected def perform_query(args : Enumerable)
       set_params args
       DummyResultSet.new self, @query
     end
 
-    protected def perform_exec(args : Slice(DB::Any))
+    protected def perform_exec(args : Enumerable)
       set_params args
-      DB::ExecResult.new 0, 0_i64
+      DB::ExecResult.new 0i64, 0_i64
     end
 
     private def set_params(args)
       @params.clear
       args.each_with_index do |arg, index|
-        @params[index] = arg
+        set_param(index, arg)
       end
     end
 
+    private def set_param(index, value : DB::Any)
+      @params[index] = value
+    end
+
+    private def set_param(index, value)
+      raise "not implemented for #{value.class}"
+    end
+
     protected def do_close
       super
     end
@@ -70,7 +78,7 @@ class DummyDriver < DB::Driver
     @values : Array(String)?
 
     @@last_result_set : self?
-    @@next_column_type : Nil.class | String.class | Int32.class | Int64.class | Float32.class | Float64.class | Slice(UInt8).class
+    @@next_column_type : Nil.class | String.class | Int32.class | Int64.class | Float32.class | Float64.class | Bytes.class
 
     def initialize(statement, query)
       super(statement)
@@ -114,12 +122,16 @@ class DummyDriver < DB::Driver
       return nil if n == "NULL"
 
       if n == "?"
-        return @statement.params[0]
+        return (@statement.as(DummyStatement)).params[0]
       end
 
       return n
     end
 
+    def read?(t : Nil.class)
+      read?.as(Nil)
+    end
+
     def read?(t : String.class)
       read?.try &.to_s
     end
@@ -140,17 +152,17 @@ class DummyDriver < DB::Driver
       read?(String).try &.to_f64
     end
 
-    def read?(t : Slice(UInt8).class)
+    def read?(t : Bytes.class)
       value = read?
       if value.is_a?(Nil)
         value
       elsif value.is_a?(String)
         ary = value.bytes
         Slice.new(ary.to_unsafe, ary.size)
-      elsif value.is_a?(Slice(UInt8))
+      elsif value.is_a?(Bytes)
         value
       else
-        raise "#{value} is not convertible to Slice(UInt8)"
+        raise "#{value} is not convertible to Bytes"
       end
     end
   end
diff --git a/spec/dummy_driver_spec.cr b/spec/dummy_driver_spec.cr
index d9bf76d..3eb2220 100644
--- a/spec/dummy_driver_spec.cr
+++ b/spec/dummy_driver_spec.cr
@@ -101,9 +101,9 @@ describe DummyDriver do
         db.query("az,AZ") do |rs|
           rs.move_next
           ary = [97u8, 122u8]
-          rs.read(Slice(UInt8)).should eq(Slice.new(ary.to_unsafe, ary.size))
+          rs.read(Bytes).should eq(Bytes.new(ary.to_unsafe, ary.size))
           ary = [65u8, 90u8]
-          rs.read(Slice(UInt8)).should eq(Slice.new(ary.to_unsafe, ary.size))
+          rs.read(Bytes).should eq(Bytes.new(ary.to_unsafe, ary.size))
         end
       end
     end
@@ -134,9 +134,9 @@ describe DummyDriver do
     it "executes and selects blob" do
       with_dummy do |db|
         ary = UInt8[0x53, 0x51, 0x4C]
-        slice = Slice.new(ary.to_unsafe, ary.size)
+        slice = Bytes.new(ary.to_unsafe, ary.size)
         DummyDriver::DummyResultSet.next_column_type = typeof(slice)
-        (db.scalar("?", slice) as Slice(UInt8)).to_a.should eq(ary)
+        (db.scalar("?", slice).as(Bytes)).to_a.should eq(ary)
       end
     end
   end
diff --git a/spec/statement_spec.cr b/spec/statement_spec.cr
index 5232621..d362ebf 100644
--- a/spec/statement_spec.cr
+++ b/spec/statement_spec.cr
@@ -9,7 +9,7 @@ describe DB::Statement do
 
   it "should initialize positional params in query" do
     with_dummy do |db|
-      stmt = db.prepare("the query")
+      stmt = db.prepare("the query").as(DummyDriver::DummyStatement)
       stmt.query "a", 1, nil
       stmt.params[0].should eq("a")
       stmt.params[1].should eq(1)
@@ -19,7 +19,7 @@ describe DB::Statement do
 
   it "should initialize positional params in query with array" do
     with_dummy do |db|
-      stmt = db.prepare("the query")
+      stmt = db.prepare("the query").as(DummyDriver::DummyStatement)
       stmt.query ["a", 1, nil]
       stmt.params[0].should eq("a")
       stmt.params[1].should eq(1)
@@ -29,7 +29,7 @@ describe DB::Statement do
 
   it "should initialize positional params in exec" do
     with_dummy do |db|
-      stmt = db.prepare("the query")
+      stmt = db.prepare("the query").as(DummyDriver::DummyStatement)
       stmt.exec "a", 1, nil
       stmt.params[0].should eq("a")
       stmt.params[1].should eq(1)
@@ -39,7 +39,7 @@ describe DB::Statement do
 
   it "should initialize positional params in exec with array" do
     with_dummy do |db|
-      stmt = db.prepare("the query")
+      stmt = db.prepare("the query").as(DummyDriver::DummyStatement)
       stmt.exec ["a", 1, nil]
       stmt.params[0].should eq("a")
       stmt.params[1].should eq(1)
@@ -49,7 +49,7 @@ describe DB::Statement do
 
   it "should initialize positional params in scalar" do
     with_dummy do |db|
-      stmt = db.prepare("the query")
+      stmt = db.prepare("the query").as(DummyDriver::DummyStatement)
       stmt.scalar "a", 1, nil
       stmt.params[0].should eq("a")
       stmt.params[1].should eq(1)
diff --git a/src/db.cr b/src/db.cr
index 65799fe..499f799 100644
--- a/src/db.cr
+++ b/src/db.cr
@@ -70,13 +70,15 @@ module DB
   # Types supported to interface with database driver.
   # These can be used in any `ResultSet#read` or any `Database#query` related
   # method to be used as query parameters
-  TYPES = [String, Int32, Int64, Float32, Float64, Slice(UInt8)]
+  TYPES = [Nil, String, Int32, Int64, Float32, Float64, Bytes]
 
-  # See `DB::TYPES` in `DB`. `Any` is a nillable version of the union of all types in `DB::TYPES`
-  alias Any = Nil | String | Int32 | Int64 | Float32 | Float64 | Slice(UInt8)
+  # See `DB::TYPES` in `DB`. `Any` is a union of all types in `DB::TYPES`
+  {% begin %}
+    alias Any = Union({{*TYPES}})
+  {% end %}
 
   # Result of a `#exec` statement.
-  record ExecResult, rows_affected : Int32, last_insert_id : Int64
+  record ExecResult, rows_affected : Int64, last_insert_id : Int64
 
   # :nodoc:
   def self.driver_class(driver_name) : Driver.class
diff --git a/src/db/query_methods.cr b/src/db/query_methods.cr
index 085ee43..517eee9 100644
--- a/src/db/query_methods.cr
+++ b/src/db/query_methods.cr
@@ -40,7 +40,7 @@ module DB
       end
     end
 
-    # Performs the `query` discarding any response
+    # Performs the `query` and returns an `ExecResult`
     def exec(query, *args)
       prepare(query).exec(*args)
     end
diff --git a/src/db/result_set.cr b/src/db/result_set.cr
index 8dbaa54..012c99e 100644
--- a/src/db/result_set.cr
+++ b/src/db/result_set.cr
@@ -16,8 +16,8 @@ module DB
   # ### Note to implementors
   #
   # 1. Override `#move_next` to move to the next row.
-  # 2. Override `#read?(t)` for all `t` in `DB::TYPES`.
-  # 3. (Optional) Override `#read(t)` for all `t` in `DB::TYPES`.
+  # 2. Override `#read?(t)` for all `t` in `DB::TYPES` and any other types the driver should handle.
+  # 3. (Optional) Override `#read(t)` for all `t` in `DB::TYPES` and any other.
   # 4. Override `#column_count`, `#column_name`.
   # 5. Override `#column_type`. It must return a type in `DB::TYPES`.
   abstract class ResultSet
@@ -59,17 +59,24 @@ module DB
     # The result is one of `DB::TYPES`.
     abstract def column_type(index : Int32)
 
+    def read(t)
+      read?(t).not_nil!
+    end
+
+    # Reads the next column as a Nil.
+    def read(t : Nil.class) : Nil
+      read?(Nil)
+    end
+
+    def read?(t)
+      raise "read?(t : #{t}) is not implemented in #{self.class}"
+    end
+
     # list datatypes that must be supported form the driver
     # users will call read(String) or read?(String) for nillables
-
     {% for t in DB::TYPES %}
       # Reads the next column as a nillable {{t}}.
       abstract def read?(t : {{t}}.class) : {{t}}?
-
-      # Reads the next column as a {{t}}.
-      def read(t : {{t}}.class) : {{t}}
-        read?({{t}}).not_nil!
-      end
     {% end %}
 
     # def read_blob
diff --git a/src/db/statement.cr b/src/db/statement.cr
index 82e7fbc..0991019 100644
--- a/src/db/statement.cr
+++ b/src/db/statement.cr
@@ -27,18 +27,18 @@ module DB
 
     # See `QueryMethods#exec`
     def exec
-      perform_exec_and_release(Slice(Any).new(0)) # no overload matches ... with types Slice(NoReturn)
+      perform_exec_and_release(Slice(Any).new(0))
     end
 
     # See `QueryMethods#exec`
-    def exec(args : Enumerable(Any))
-      perform_exec_and_release(args.to_a.to_unsafe.to_slice(args.size))
+    def exec(args : Array)
+      perform_exec_and_release(args)
     end
 
     # See `QueryMethods#exec`
     def exec(*args)
       # TODO better way to do it
-      perform_exec_and_release(args.to_a.to_unsafe.to_slice(args.size))
+      perform_exec_and_release(args)
     end
 
     # See `QueryMethods#scalar`
@@ -57,8 +57,8 @@ module DB
             return rs.read?(Float32)
           when Float64.class
             return rs.read?(Float64)
-          when Slice(UInt8).class
-            return rs.read?(Slice(UInt8))
+          when Bytes.class
+            return rs.read?(Bytes)
           when Nil.class
             return rs.read?(Int32)
           else
@@ -71,13 +71,23 @@ module DB
     end
 
     # See `QueryMethods#query`
-    def query(*args)
-      perform_query *args
+    def query
+      perform_query Slice(Any).new(0)
+    end
+
+    # See `QueryMethods#query`
+    def query(args : Array)
+      perform_query args
     end
 
     # See `QueryMethods#query`
     def query(*args)
-      perform_query(*args).tap do |rs|
+      perform_query args
+    end
+
+    # See `QueryMethods#query`
+    def query(*args)
+      query(*args).tap do |rs|
         begin
           yield rs
         ensure
@@ -86,27 +96,13 @@ module DB
       end
     end
 
-    private def perform_query : ResultSet
-      perform_query(Slice(Any).new(0)) # no overload matches ... with types Slice(NoReturn)
-    end
-
-    private def perform_query(args : Enumerable(Any)) : ResultSet
-      # TODO better way to do it
-      perform_query(args.to_a.to_unsafe.to_slice(args.size))
-    end
-
-    private def perform_query(*args) : ResultSet
-      # TODO better way to do it
-      perform_query(args.to_a.to_unsafe.to_slice(args.size))
-    end
-
-    private def perform_exec_and_release(args : Slice(Any)) : ExecResult
+    private def perform_exec_and_release(args : Enumerable) : ExecResult
       perform_exec(args).tap do
         release_connection
       end
     end
 
-    protected abstract def perform_query(args : Slice(Any)) : ResultSet
-    protected abstract def perform_exec(args : Slice(Any)) : ExecResult
+    protected abstract def perform_query(args : Enumerable) : ResultSet
+    protected abstract def perform_exec(args : Enumerable) : ExecResult
   end
 end