diff --git a/spec/custom_drivers_types_spec.cr b/spec/custom_drivers_types_spec.cr
index 11267f4..1a4f333 100644
--- a/spec/custom_drivers_types_spec.cr
+++ b/spec/custom_drivers_types_spec.cr
@@ -66,12 +66,21 @@ class FooDriver < DB::Driver
 
   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
@@ -120,12 +129,21 @@ class BarDriver < DB::Driver
 
   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
@@ -232,7 +250,7 @@ describe DB do
       db.query "query", 1, "string" { }
       db.query("query", Slice(UInt8).new(4)) { }
       db.query("query", 1, "string", BarValue.new(5)) { }
-      db.query "query", [1, "string", FooValue.new(5)] { }
+      db.query "query", [1, "string", BarValue.new(5)] { }
 
       db.query("query").close
       db.query("query", 1).close
@@ -264,4 +282,18 @@ describe DB do
       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 21f724e..e9b4ffc 100644
--- a/spec/dummy_driver.cr
+++ b/spec/dummy_driver.cr
@@ -55,10 +55,18 @@ class DummyDriver < DB::Driver
     private def set_params(args)
       @params.clear
       args.each_with_index do |arg, index|
-        @params[index] = arg.as(DB::Any)
+        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