diff --git a/mix/QBigInt.cpp b/mix/QBigInt.cpp
index 21d32a9c3..ee29cea43 100644
--- a/mix/QBigInt.cpp
+++ b/mix/QBigInt.cpp
@@ -57,3 +57,38 @@ QBigInt* QBigInt::divide(QBigInt* const& _value) const
 	BigIntVariant toDivide = _value->internalValue();
 	return new QBigInt(boost::apply_visitor(mix::divide(), m_internalValue, toDivide));
 }
+
+QVariantMap QBigInt::checkAgainst(QString const& _type) const
+{
+	QVariantMap ret;
+	QString type = _type;
+	QString capacity = type.replace("uint", "").replace("int", "");
+	if (capacity.isEmpty())
+		capacity = "256";
+	bigint range = 256^(capacity.toInt() / 8);
+	bigint value = boost::get<bigint>(this->internalValue());
+	ret.insert("valid", true);
+	if (_type.startsWith("uint") && value > range - 1)
+	{
+		ret.insert("minValue", "0");
+		std::ostringstream s;
+		s << range - 1;
+		ret.insert("maxValue", QString::fromStdString(s.str()));
+		if (value > range)
+			ret["valid"] = false;
+	}
+	else if (_type.startsWith("int"))
+	{
+		range = range / 2;
+		std::ostringstream s;
+		s << -range;
+		ret.insert("minValue", QString::fromStdString(s.str()));
+		s.str("");
+		s.clear();
+		s << range - 1;
+		ret.insert("maxValue", QString::fromStdString(s.str()));
+		if (-range > value || value > range - 1)
+			ret["valid"] = false;
+	}
+	return ret;
+}
diff --git a/mix/QBigInt.h b/mix/QBigInt.h
index b549a16db..ccf487d2a 100644
--- a/mix/QBigInt.h
+++ b/mix/QBigInt.h
@@ -84,6 +84,7 @@ public:
 	Q_INVOKABLE QString value() const;
 	/// Set the value of the BigInteger used. Will use u256 type. Invokable from QML.
 	Q_INVOKABLE void setValue(QString const& _value) { m_internalValue = dev::jsToU256(_value.toStdString()); }
+	Q_INVOKABLE void setBigInt(QString const& _value) { m_internalValue = bigint(_value.toStdString()); }
 	/// Subtract by @a _value. Invokable from QML.
 	Q_INVOKABLE QBigInt* subtract(QBigInt* const& _value) const;
 	/// Add @a _value to the current big integer. Invokable from QML.
@@ -92,6 +93,8 @@ public:
 	Q_INVOKABLE QBigInt* multiply(QBigInt* const& _value) const;
 	/// divide by @a _value. Invokable from QML.
 	Q_INVOKABLE QBigInt* divide(QBigInt* const& _value) const;
+	/// check if the current value satisfy the given type
+	Q_INVOKABLE QVariantMap checkAgainst(QString const& _type) const;
 
 protected:
 	 BigIntVariant m_internalValue;
diff --git a/mix/qml/TransactionDialog.qml b/mix/qml/TransactionDialog.qml
index a4c896d3f..df5ad781b 100644
--- a/mix/qml/TransactionDialog.qml
+++ b/mix/qml/TransactionDialog.qml
@@ -515,7 +515,7 @@ Dialog {
 						}
 						else
 						{
-							errorDialog.text = qsTr("some parameters are invalid:\n");
+							errorDialog.text = qsTr("Some parameters are invalid:\n");
 							for (var k in invalid)
 								errorDialog.text += invalid[k].message + "\n";
 							errorDialog.open();
diff --git a/mix/qml/js/InputValidator.js b/mix/qml/js/InputValidator.js
index 6e94dec6e..37185b898 100644
--- a/mix/qml/js/InputValidator.js
+++ b/mix/qml/js/InputValidator.js
@@ -1,3 +1,5 @@
+Qt.include("QEtherHelper.js")
+
 var nbRegEx = new RegExp('^[0-9]+$');
 function validate(model, values)
 {
@@ -8,7 +10,9 @@ function validate(model, values)
 		{
 			var type = model[k].type.name;
 			var res;
-			if (type.indexOf("int") !== -1)
+			if (isContractType(type))
+				res = validateAddress(type, values[model[k].name]);
+			else if (type.indexOf("int") !== -1)
 				res = validateInt(type, values[model[k].name]);
 			else if (type.indexOf("bytes") !== -1)
 				res = validateBytes(type, values[model[k].name]);
@@ -17,7 +21,7 @@ function validate(model, values)
 			else if (type.indexOf("address") !== -1)
 				res = validateAddress(type, values[model[k].name]);
 			else
-				res = validateAddress(type, values[model[k].name]); //we suppose that this is a ctr type.
+				res.valid = true;
 			if (!res.valid)
 				inError.push({ type: type, value: values, message: res.message });
 		}
@@ -25,6 +29,16 @@ function validate(model, values)
 	return inError;
 }
 
+function isContractType(_type)
+{
+	for (var k in Object.keys(codeModel.contracts))
+	{
+		if ("contract " + Object.keys(codeModel.contracts)[k] === _type)
+			return true;
+	}
+	return false;
+}
+
 function validateInt(_type, _value)
 {
 	var ret = { valid: true, message: "" }
@@ -35,7 +49,6 @@ function validateInt(_type, _value)
 		{
 			ret.valid = false;
 			ret.message = "uint type cannot represent negative number";
-			return false;
 		}
 	}
 	ret.valid = nbRegEx.test(_value);
@@ -43,12 +56,13 @@ function validateInt(_type, _value)
 		ret.message = _value + " does not represent " + _type + " type.";
 	else
 	{
-		var t = _type.replace("uint", "").replace("int", "");
-		var max = parseInt(t) / 4;
-		if (_value.length > max)
+		var bigInt = createBigInt(_value);
+		bigInt.setBigInt(_value);
+		var result = bigInt.checkAgainst(_type);
+		if (!result.valid)
 		{
 			ret.valid = false;
-			ret.message = _type + " should not contains more than " + max + " digits";
+			ret.message = _type + " should be between " + result.minValue + " and " + result.maxValue;
 		}
 	}
 	return ret;
@@ -60,7 +74,6 @@ function validateAddress(_type, _value)
 	if (_value.indexOf("<") === 0 && _value.indexOf(">") === _value.length - 1)
 	{
 		var v = _value.split(' - ');
-		console.log(JSON.stringify(v));
 		if (v.length !== 2 || !nbRegEx.test(v[1].replace(">", ""))) // <Contract - 2>
 		{
 			ret.valid = false;