diff --git a/src/fields/color.jsx b/src/fields/color.jsx
index 4c1895c..26ad8fb 100644
--- a/src/fields/color.jsx
+++ b/src/fields/color.jsx
@@ -11,9 +11,13 @@ static propTypes = {
     doc: React.PropTypes.string,
   }
 
+	onChange(e) {
+		return this.props.onChange(e.target.value)
+	}
+
 	render() {
 		return <Input
-			onChange={this.props.onChange}
+			onChange={this.onChange.bind(this)}
 			label={this.props.name}
 			name={this.props.name}
 			value={this.props.value}
diff --git a/src/fields/enum.jsx b/src/fields/enum.jsx
index dc74020..3795de1 100644
--- a/src/fields/enum.jsx
+++ b/src/fields/enum.jsx
@@ -10,12 +10,16 @@ class EnumField extends React.Component {
     doc: React.PropTypes.string,
   }
 
+	onChange(e) {
+		return this.props.onChange(e.target.value)
+	}
+
 	render() {
 		const options = this.props.allowedValues.map(val => {
 			return {children: val, value: val}
 		})
 		return <Select
-			onChange={this.props.onChange}
+			onChange={this.onChange.bind(this)}
 			name={this.props.name}
 			options={options}
 			label={this.props.name}
diff --git a/src/fields/number.jsx b/src/fields/number.jsx
index 4b764a7..996325c 100644
--- a/src/fields/number.jsx
+++ b/src/fields/number.jsx
@@ -14,9 +14,14 @@ class NumberField extends React.Component {
     doc: React.PropTypes.string,
   }
 
+	onChange(e) {
+		return this.props.onChange(parseFloat(e.target.value))
+	}
+
 	render() {
-		return <Input type="number"
-			onChange={this.props.onChange}
+		return <Input
+			type="number"
+			onChange={this.onChange.bind(this)}
 			label={this.props.name}
 			name={this.props.name}
 			message={this.props.doc}
diff --git a/src/fields/spec.jsx b/src/fields/spec.jsx
index b20ff5d..f6871a1 100644
--- a/src/fields/spec.jsx
+++ b/src/fields/spec.jsx
@@ -18,8 +18,8 @@ class SpecField extends React.Component {
     ]).isRequired,
   }
 
-	onValueChanged(property, e) {
-		return this.props.onChange(property, e.target.value)
+	onValueChanged(property, value) {
+		return this.props.onChange(property, value)
 	}
 
 	render() {
diff --git a/src/fields/string.jsx b/src/fields/string.jsx
index b1b1f2d..191e2b3 100644
--- a/src/fields/string.jsx
+++ b/src/fields/string.jsx
@@ -6,14 +6,18 @@ class StringField extends React.Component {
 static propTypes = {
     onChange: React.PropTypes.func.isRequired,
 		name: React.PropTypes.string.isRequired,
-    value: React.PropTypes.number,
+    value: React.PropTypes.string,
     default: React.PropTypes.number,
     doc: React.PropTypes.string,
   }
 
+	onChange(e) {
+		return this.props.onChange(e.target.value)
+	}
+
 	render() {
 		return <Input
-			onChange={this.props.onChange}
+			onChange={this.onChange.bind(this)}
 			label={this.props.name}
 			name={this.props.name}
 			value={this.props.value}