diff --git a/examples/rich-text/index.js b/examples/rich-text/index.js
index 8ff1d9444..dd2bcc6b3 100644
--- a/examples/rich-text/index.js
+++ b/examples/rich-text/index.js
@@ -59,7 +59,7 @@ class RichText extends React.Component {
 
   state = {
     state: Raw.deserialize(initialState, { terse: true })
-  };
+  }
 
   /**
    * Check if the current selection has a mark with `type` in it.
diff --git a/src/components/content.js b/src/components/content.js
index 2c80833ff..43f993967 100644
--- a/src/components/content.js
+++ b/src/components/content.js
@@ -9,13 +9,14 @@ import TRANSFER_TYPES from '../constants/transfer-types'
 import Base64 from '../serializers/base-64'
 import Node from './node'
 import Selection from '../models/selection'
+import SlateTypes from '../utils/prop-types'
 import extendSelection from '../utils/extend-selection'
 import findClosestNode from '../utils/find-closest-node'
 import findDeepestNode from '../utils/find-deepest-node'
+import getHtmlFromNativePaste from '../utils/get-html-from-native-paste'
 import getPoint from '../utils/get-point'
 import getTransferData from '../utils/get-transfer-data'
 import setTransferData from '../utils/set-transfer-data'
-import getHtmlFromNativePaste from '../utils/get-html-from-native-paste'
 import { IS_FIREFOX, IS_MAC, IS_IE } from '../constants/environment'
 
 /**
@@ -58,12 +59,12 @@ class Content extends React.Component {
     onSelect: Types.func.isRequired,
     readOnly: Types.bool.isRequired,
     role: Types.string,
-    schema: Types.object,
+    schema: SlateTypes.schema.isRequired,
     spellCheck: Types.bool.isRequired,
-    state: Types.object.isRequired,
+    state: SlateTypes.state.isRequired,
     style: Types.object,
     tabIndex: Types.number,
-    tagName: Types.string
+    tagName: Types.string,
   }
 
   /**
@@ -74,7 +75,7 @@ class Content extends React.Component {
 
   static defaultProps = {
     style: {},
-    tagName: 'div'
+    tagName: 'div',
   }
 
   /**
diff --git a/src/components/editor.js b/src/components/editor.js
index 5198a702a..58525f401 100644
--- a/src/components/editor.js
+++ b/src/components/editor.js
@@ -6,7 +6,7 @@ import Types from 'prop-types'
 
 import Stack from '../models/stack'
 import State from '../models/state'
-import SlatePropTypes from '../utils/prop-types'
+import SlateTypes from '../utils/prop-types'
 import noop from '../utils/noop'
 
 /**
@@ -81,7 +81,7 @@ class Editor extends React.Component {
     role: Types.string,
     schema: Types.object,
     spellCheck: Types.bool,
-    state: SlatePropTypes.state.isRequired,
+    state: SlateTypes.state.isRequired,
     style: Types.object,
     tabIndex: Types.number,
   }
diff --git a/src/components/leaf.js b/src/components/leaf.js
index 2a370a01a..d928845d4 100644
--- a/src/components/leaf.js
+++ b/src/components/leaf.js
@@ -5,6 +5,7 @@ import ReactDOM from 'react-dom'
 import Types from 'prop-types'
 
 import OffsetKey from '../utils/offset-key'
+import SlateTypes from '../utils/prop-types'
 import findDeepestNode from '../utils/find-deepest-node'
 import { IS_FIREFOX } from '../constants/environment'
 
@@ -31,17 +32,17 @@ class Leaf extends React.Component {
    */
 
   static propTypes = {
-    block: Types.object.isRequired,
+    block: SlateTypes.block.isRequired,
     editor: Types.object.isRequired,
     index: Types.number.isRequired,
-    marks: Types.object.isRequired,
-    node: Types.object.isRequired,
+    marks: SlateTypes.marks.isRequired,
+    node: SlateTypes.node.isRequired,
     offset: Types.number.isRequired,
-    parent: Types.object.isRequired,
-    ranges: Types.object.isRequired,
-    schema: Types.object.isRequired,
-    state: Types.object.isRequired,
-    text: Types.string.isRequired
+    parent: SlateTypes.node.isRequired,
+    ranges: SlateTypes.ranges.isRequired,
+    schema: SlateTypes.schema.isRequired,
+    state: SlateTypes.state.isRequired,
+    text: Types.string.isRequired,
   }
 
   /**
diff --git a/src/components/node.js b/src/components/node.js
index 570354456..5847a2e95 100644
--- a/src/components/node.js
+++ b/src/components/node.js
@@ -7,6 +7,7 @@ import Types from 'prop-types'
 import TRANSFER_TYPES from '../constants/transfer-types'
 import Base64 from '../serializers/base-64'
 import Leaf from './leaf'
+import SlateTypes from '../utils/prop-types'
 import Void from './void'
 import getWindow from 'get-window'
 import scrollToSelection from '../utils/scroll-to-selection'
@@ -35,13 +36,13 @@ class Node extends React.Component {
    */
 
   static propTypes = {
-    block: Types.object,
+    block: SlateTypes.block,
     editor: Types.object.isRequired,
-    node: Types.object.isRequired,
-    parent: Types.object.isRequired,
+    node: SlateTypes.node.isRequired,
+    parent: SlateTypes.node.isRequired,
     readOnly: Types.bool.isRequired,
-    schema: Types.object.isRequired,
-    state: Types.object.isRequired
+    schema: SlateTypes.schema.isRequired,
+    state: SlateTypes.state.isRequired,
   }
 
   /**
diff --git a/src/components/placeholder.js b/src/components/placeholder.js
index 2387cc917..63f35abc8 100644
--- a/src/components/placeholder.js
+++ b/src/components/placeholder.js
@@ -2,6 +2,8 @@
 import React from 'react'
 import Types from 'prop-types'
 
+import SlateTypes from '../utils/prop-types'
+
 /**
  * Placeholder.
  *
@@ -20,10 +22,10 @@ class Placeholder extends React.Component {
     children: Types.any.isRequired,
     className: Types.string,
     firstOnly: Types.bool,
-    node: Types.object.isRequired,
-    parent: Types.object,
-    state: Types.object.isRequired,
-    style: Types.object
+    node: SlateTypes.node.isRequired,
+    parent: SlateTypes.node,
+    state: SlateTypes.state.isRequired,
+    style: Types.object,
   }
 
   /**
@@ -33,7 +35,7 @@ class Placeholder extends React.Component {
    */
 
   static defaultProps = {
-    firstOnly: true
+    firstOnly: true,
   }
 
   /**
diff --git a/src/components/void.js b/src/components/void.js
index 0dd1cf14f..042b050a2 100644
--- a/src/components/void.js
+++ b/src/components/void.js
@@ -6,6 +6,7 @@ import Types from 'prop-types'
 import Leaf from './leaf'
 import Mark from '../models/mark'
 import OffsetKey from '../utils/offset-key'
+import SlateTypes from '../utils/prop-types'
 import { IS_FIREFOX } from '../constants/environment'
 
 /**
@@ -31,14 +32,14 @@ class Void extends React.Component {
    */
 
   static propTypes = {
-    block: Types.object,
+    block: SlateTypes.block,
     children: Types.any.isRequired,
     editor: Types.object.isRequired,
-    node: Types.object.isRequired,
-    parent: Types.object.isRequired,
+    node: SlateTypes.node.isRequired,
+    parent: SlateTypes.node.isRequired,
     readOnly: Types.bool.isRequired,
-    schema: Types.object.isRequired,
-    state: Types.object.isRequired,
+    schema: SlateTypes.schema.isRequired,
+    state: SlateTypes.state.isRequired,
   }
 
   /**
@@ -49,7 +50,7 @@ class Void extends React.Component {
 
   state = {
     dragCounter: 0,
-    editable: false
+    editable: false,
   }
 
   /**
diff --git a/src/models/block.js b/src/models/block.js
index 52f739bdd..2cd522ae8 100644
--- a/src/models/block.js
+++ b/src/models/block.js
@@ -108,6 +108,17 @@ class Block extends Record(DEFAULTS) {
     return !!(value && value[MODEL_TYPES.BLOCK])
   }
 
+  /**
+   * Check if a `value` is a block list.
+   *
+   * @param {Any} value
+   * @return {Boolean}
+   */
+
+  static isBlockList(value) {
+    return List.isList(value) && value.size > 0 && Block.isBlock(value.first())
+  }
+
   /**
    * Get the node's kind.
    *
diff --git a/src/models/character.js b/src/models/character.js
index 3c81826a4..7ac4a1a50 100644
--- a/src/models/character.js
+++ b/src/models/character.js
@@ -85,6 +85,17 @@ class Character extends Record(DEFAULTS) {
     return !!(value && value[MODEL_TYPES.CHARACTER])
   }
 
+  /**
+   * Check if a `value` is a character list.
+   *
+   * @param {Any} value
+   * @return {Boolean}
+   */
+
+  static isCharacterList(value) {
+    return List.isList(value) && value.size > 0 && Character.isCharacter(value.first())
+  }
+
   /**
    * Deprecated.
    */
diff --git a/src/models/inline.js b/src/models/inline.js
index 61187493d..ee1dbbf40 100644
--- a/src/models/inline.js
+++ b/src/models/inline.js
@@ -108,6 +108,17 @@ class Inline extends Record(DEFAULTS) {
     return !!(value && value[MODEL_TYPES.INLINE])
   }
 
+  /**
+   * Check if a `value` is a list of inlines.
+   *
+   * @param {Any} value
+   * @return {Boolean}
+   */
+
+  static isInlineList(value) {
+    return List.isList(value) && value.size > 0 && Inline.isInline(value.first())
+  }
+
   /**
    * Get the node's kind.
    *
diff --git a/src/models/mark.js b/src/models/mark.js
index 0f62fbb21..bfcb4e5a3 100644
--- a/src/models/mark.js
+++ b/src/models/mark.js
@@ -118,6 +118,17 @@ class Mark extends Record(DEFAULTS) {
     return !!(value && value[MODEL_TYPES.MARK])
   }
 
+  /**
+   * Check if a `value` is a set of marks.
+   *
+   * @param {Any} value
+   * @return {Boolean}
+   */
+
+  static isMarkSet(value) {
+    return Set.isSet(value) && value.size > 0 && Mark.isMark(value.first())
+  }
+
   /**
    * Get the kind.
    */
diff --git a/src/models/node.js b/src/models/node.js
index 36a14f99f..7794069a2 100644
--- a/src/models/node.js
+++ b/src/models/node.js
@@ -113,6 +113,17 @@ class Node {
     )
   }
 
+  /**
+   * Check if a `value` is a list of nodes.
+   *
+   * @param {Any} value
+   * @return {Boolean}
+   */
+
+  static isNodeList(value) {
+    return List.isList(value) && value.size > 0 && Node.isNode(value.first())
+  }
+
   /**
    * True if the node has both descendants in that order, false otherwise. The
    * order is depth-first, post-order.
diff --git a/src/models/range.js b/src/models/range.js
index 90c466aa3..42ce22dbd 100644
--- a/src/models/range.js
+++ b/src/models/range.js
@@ -3,7 +3,7 @@ import MODEL_TYPES from '../constants/model-types'
 import Character from './character'
 import Mark from './mark'
 import isPlainObject from 'is-plain-object'
-import { Record, Set } from 'immutable'
+import { List, Record, Set } from 'immutable'
 
 /**
  * Default properties.
@@ -64,6 +64,17 @@ class Range extends Record(DEFAULTS) {
     return !!(value && value[MODEL_TYPES.RANGE])
   }
 
+  /**
+   * Check if a `value` is a list of ranges.
+   *
+   * @param {Any} value
+   * @return {Boolean}
+   */
+
+  static isRangeList(value) {
+    return List.isList(value) && value.size > 0 && Range.isRange(value.first())
+  }
+
   /**
    * Get the node's kind.
    *
diff --git a/src/models/text.js b/src/models/text.js
index 449291329..6f354702c 100644
--- a/src/models/text.js
+++ b/src/models/text.js
@@ -94,6 +94,17 @@ class Text extends Record(DEFAULTS) {
     return !!(value && value[MODEL_TYPES.TEXT])
   }
 
+  /**
+   * Check if a `value` is a list of texts.
+   *
+   * @param {Any} value
+   * @return {Boolean}
+   */
+
+  static isTextList(value) {
+    return List.isList(value) && value.size > 0 && Text.isText(value.first())
+  }
+
   /**
    * Deprecated.
    */
diff --git a/src/utils/extend-selection.js b/src/utils/extend-selection.js
index 1ec8f2596..00dfaa2c6 100644
--- a/src/utils/extend-selection.js
+++ b/src/utils/extend-selection.js
@@ -1,41 +1,49 @@
 
 /**
- * Extends the given selection to a given node and offset
+ * Extends a DOM `selection` to a given `el` and `offset`.
  *
- * @param {Selection} selection Selection instance
- * @param {Element} el Node to extend to
- * @param {Number} offset Text offset to extend to
- * @returns {Selection} Mutated Selection instance
+ * COMPAT: In IE11, `selection.extend` doesn't exist natively, so we have to
+ * polyfill it with this. (2017/09/06)
+ *
+ * https://gist.github.com/tyler-johnson/0a3e8818de3f115b2a2dc47468ac0099
+ *
+ * @param {Selection} selection
+ * @param {Element} el
+ * @param {Number} offset
+ * @return {Selection}
  */
 
 function extendSelection(selection, el, offset) {
-  // Use native method when possible
-  if (typeof selection.extend === 'function') return selection.extend(el, offset)
+  // Use native method whenever possible.
+  if (typeof selection.extend === 'function') {
+    return selection.extend(el, offset)
+  }
 
-  // See https://gist.github.com/tyler-johnson/0a3e8818de3f115b2a2dc47468ac0099
   const range = document.createRange()
   const anchor = document.createRange()
-  anchor.setStart(selection.anchorNode, selection.anchorOffset)
-
   const focus = document.createRange()
+  anchor.setStart(selection.anchorNode, selection.anchorOffset)
   focus.setStart(el, offset)
 
   const v = focus.compareBoundaryPoints(Range.START_TO_START, anchor)
-  if (v >= 0) { // Focus is after anchor
+
+  // If the focus is after the anchor...
+  if (v >= 0) {
     range.setStart(selection.anchorNode, selection.anchorOffset)
     range.setEnd(el, offset)
-  } else { // Anchor is after focus
+  }
+
+  // Otherwise, if the anchor if after the focus...
+  else {
     range.setStart(el, offset)
     range.setEnd(selection.anchorNode, selection.anchorOffset)
   }
 
   selection.removeAllRanges()
   selection.addRange(range)
-
   return selection
 }
 
-
 /**
  * Export.
  *
diff --git a/src/utils/find-closest-node.js b/src/utils/find-closest-node.js
index f55177acf..134c1bdde 100644
--- a/src/utils/find-closest-node.js
+++ b/src/utils/find-closest-node.js
@@ -2,6 +2,11 @@
 /**
  * Find the closest ancestor of a DOM `element` that matches a given selector.
  *
+ * COMPAT: In IE11, the `Node.closest` method doesn't exist natively, so we
+ * have to polyfill it. (2017/09/06)
+ *
+ * https://developer.mozilla.org/en-US/docs/Web/API/Element/closest#Polyfill
+ *
  * @param {Element} node
  * @param {String} selector
  * @return {Element}
@@ -10,10 +15,10 @@
 function findClosestNode(node, selector) {
   if (typeof node.closest === 'function') return node.closest(selector)
 
-  // See https://developer.mozilla.org/en-US/docs/Web/API/Element/closest#Polyfill
   const matches = (node.document || node.ownerDocument).querySelectorAll(selector)
-  let i
   let parentNode = node
+  let i
+
   do {
     i = matches.length
     while (--i >= 0 && matches.item(i) !== parentNode);
diff --git a/src/utils/find-dom-node.js b/src/utils/find-dom-node.js
index 1292b1be2..2702bee8d 100644
--- a/src/utils/find-dom-node.js
+++ b/src/utils/find-dom-node.js
@@ -10,9 +10,7 @@ function findDOMNode(node) {
   const el = window.document.querySelector(`[data-key="${node.key}"]`)
 
   if (!el) {
-    throw new Error(`Unable to find a DOM node for "${node.key}". This is
-often because of forgetting to add \`props.attributes\` to a component
-returned from \`renderNode\`.`)
+    throw new Error(`Unable to find a DOM node for "${node.key}". This is often because of forgetting to add \`props.attributes\` to a component returned from \`renderNode\`.`)
   }
 
   return el
diff --git a/src/utils/get-html-from-native-paste.js b/src/utils/get-html-from-native-paste.js
index 71efc853e..bdc40b140 100644
--- a/src/utils/get-html-from-native-paste.js
+++ b/src/utils/get-html-from-native-paste.js
@@ -1,3 +1,4 @@
+
 import { findDOMNode } from 'react-dom'
 
 /**
@@ -7,28 +8,27 @@ import { findDOMNode } from 'react-dom'
  * is needed to return the HTML content. This solution was adapted from
  * http://stackoverflow.com/a/6804718.
  *
- * @param {React.Component} component
+ * @param {Component} component
  * @param {Function} callback
  */
 
 function getHtmlFromNativePaste(component, callback) {
   const el = findDOMNode(component)
 
-  // Clone contentedible element, move out of screen and set focus.
+  // Create an off-screen clone of the element and give it focus.
   const clone = el.cloneNode()
   clone.setAttribute('class', '')
   clone.setAttribute('style', 'position: fixed; left: -9999px')
   el.parentNode.insertBefore(clone, el)
   clone.focus()
 
-  // Clear call stack to let native paste behaviour occur on cloned element,
-  // then get what was pasted from the DOM and remove cloned element.
+  // Tick forward so the native paste behaviour occurs in cloned element and we
+  // can get what was pasted from the DOM.
   setTimeout(() => {
     if (clone.childElementCount > 0) {
       // If the node contains any child nodes, that is the HTML content.
       const html = clone.innerHTML
       clone.parentNode.removeChild(clone)
-
       callback(html)
     } else {
       // Only plain text, no HTML.
diff --git a/src/utils/prop-types.js b/src/utils/prop-types.js
index c0111670b..12b9ff2b4 100644
--- a/src/utils/prop-types.js
+++ b/src/utils/prop-types.js
@@ -1,172 +1,84 @@
+
+import { Set } from 'immutable'
+
 import Block from '../models/block'
+import Change from '../models/change'
 import Character from '../models/character'
+import Data from '../models/data'
 import Document from '../models/document'
+import History from '../models/history'
 import Inline from '../models/inline'
 import Mark from '../models/mark'
+import Node from '../models/node'
 import Range from '../models/range'
 import Schema from '../models/schema'
 import Selection from '../models/selection'
+import Stack from '../models/stack'
 import State from '../models/state'
 import Text from '../models/text'
 
 /**
- * HOC Function that takes in a predicate prop type function, and allows an isRequired chain
+ * Create a prop type checker for Slate objects with `name` and `validate`.
  *
- * @param {Function} predicate
+ * @param {String} name
+ * @param {Function} validate
  * @return {Function}
  */
 
-function createChainablePropType(predicate) {
-  function propType(props, propName, componentName) {
-    if (props[propName] == null) return
-
-    return predicate(props, propName, componentName)
+function create(name, validate) {
+  function check(isRequired, props, propName, componentName, location) {
+    const value = props[propName]
+    if (value == null && !isRequired) return null
+    if (value == null && isRequired) return new Error(`The ${location} \`${propName}\` is marked as required in \`${componentName}\`, but it was not supplied.`)
+    if (validate(value)) return null
+    return new Error(`Invalid ${location} \`${propName}\` supplied to \`${componentName}\`, expected a Slate \`${name}\` but received: ${value}`)
   }
 
-  propType.isRequired = (props, propName, componentName) => {
-    if (props[propName] == null) return new Error(`Required prop \`${propName}\` was not specified in \`${componentName}\`.`)
+  function propType(...args) {
+    return check(false, ...args)
+  }
 
-    return predicate(props, propName, componentName)
+  propType.isRequired = function (...args) {
+    return check(true, ...args)
   }
 
   return propType
 }
 
 /**
- * Exported Slate proptype that checks if a prop is a Slate Block
- *
- * @type {Function}
- */
-
-const block = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Block.isBlock(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Block`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Character
- *
- * @type {Function}
- */
-
-const character = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Character.isCharacter(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Character`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Document
- *
- * @type {Function}
- */
-
-const document = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Document.isDocument(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Document`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Inline
- *
- * @type {Function}
- */
-
-const inline = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Inline.isInline(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Inline`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Mark
- *
- * @type {Function}
- */
-
-const mark = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Mark.isMark(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Mark`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Range
- *
- * @type {Function}
- */
-
-const range = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Range.isRange(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Range`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Schema
- *
- * @type {Function}
- */
-
-const schema = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Schema.isSchema(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Schema`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Selection
- *
- * @type {Function}
- */
-
-const selection = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Selection.isSelection(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Selection`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate State
- *
- * @type {Function}
- */
-
-const state = createChainablePropType(
-  (props, propName, componentName) => {
-    return !State.isState(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate State ${props[propName]}`) : null
-  }
-)
-
-/**
- * Exported Slate proptype that checks if a prop is a Slate Text
- *
- * @type {Function}
- */
-
-const text = createChainablePropType(
-  (props, propName, componentName) => {
-    return !Text.isText(props[propName]) ? new Error(`${propName} in ${componentName} is not a Slate Text`) : null
-  }
-)
-
-/**
- * Exported Slate proptypes
+ * Prop type checkers.
  *
  * @type {Object}
  */
 
-export default {
-  block,
-  character,
-  document,
-  inline,
-  mark,
-  range,
-  schema,
-  selection,
-  state,
-  text,
+const Types = {
+  block: create('Block', v => Block.isBlock(v)),
+  blocks: create('List<Block>', v => Block.isBlockList(v)),
+  change: create('Change', v => Change.isChange(v)),
+  character: create('Character', v => Character.isCharacter(v)),
+  characters: create('List<Character>', v => Character.isCharacterList(v)),
+  data: create('Data', v => Data.isData(v)),
+  document: create('Document', v => Document.isDocument(v)),
+  history: create('History', v => History.isHistory(v)),
+  inline: create('Inline', v => Inline.isInline(v)),
+  mark: create('Mark', v => Mark.isMark(v)),
+  marks: create('Set<Mark>', v => (Set.isSet(v) && v.size === 0) || Mark.isMarkSet(v)),
+  node: create('Node', v => Node.isNode(v)),
+  nodes: create('List<Node>', v => Node.isNodeList(v)),
+  range: create('Range', v => Range.isRange(v)),
+  ranges: create('List<Range>', v => Range.isRangeList(v)),
+  schema: create('Schema', v => Schema.isSchema(v)),
+  selection: create('Selection', v => Selection.isSelection(v)),
+  stack: create('Stack', v => Stack.isStack(v)),
+  state: create('State', v => State.isState(v)),
+  text: create('Text', v => Text.isText(v)),
+  texts: create('List<Text>', v => Text.isTextList(v)),
 }
+
+/**
+ * Export.
+ *
+ * @type {Object}
+ */
+
+export default Types
diff --git a/src/utils/set-transfer-data.js b/src/utils/set-transfer-data.js
index 3143cd676..95eecc580 100644
--- a/src/utils/set-transfer-data.js
+++ b/src/utils/set-transfer-data.js
@@ -1,5 +1,7 @@
+
 /**
- * Set data on dataTransfer
+ * Set data with `type` and `content` on a `dataTransfer` object.
+ *
  * COMPAT: In Edge, custom types throw errors, so embed all non-standard
  * types in text/plain compound object. (2017/7/12)
  *
@@ -13,23 +15,26 @@ function setTransferData(dataTransfer, type, content) {
     dataTransfer.setData(type, content)
   } catch (err) {
     const prefix = 'SLATE-DATA-EMBED::'
-    let obj = {}
     const text = dataTransfer.getData('text/plain')
+    let obj = {}
 
-    // If prefixed, assume embedded drag data
+    // If the existing plain text data is prefixed, it's Slate JSON data.
     if (text.substring(0, prefix.length) === prefix) {
       try {
         obj = JSON.parse(text.substring(prefix.length))
-      } catch (err2) {
-        throw new Error('Unable to parse custom embedded drag data')
+      } catch (e) {
+        throw new Error('Failed to parse Slate data from `DataTransfer` object.')
       }
-    } else {
+    }
+
+    // Otherwise, it's just set it as is.
+    else {
       obj['text/plain'] = text
     }
 
     obj[type] = content
-
-    dataTransfer.setData('text/plain', `${prefix}${JSON.stringify(obj)}`)
+    const string = `${prefix}${JSON.stringify(obj)}`
+    dataTransfer.setData('text/plain', string)
   }
 }