diff --git a/lib/models/transforms.js b/lib/models/transforms.js
index d0d9543ee..05717dcf3 100644
--- a/lib/models/transforms.js
+++ b/lib/models/transforms.js
@@ -7,6 +7,7 @@ import Inline from './inline'
 import Mark from './mark'
 import Selection from './selection'
 import Text from './text'
+import typeOf from 'type-of'
 import uid from '../utils/uid'
 import { List, Map, Set } from 'immutable'
 
@@ -22,7 +23,7 @@ const Transforms = {
    * Add a new `mark` to the characters at `range`.
    *
    * @param {Selection} range
-   * @param {Mark or String} mark
+   * @param {Mark or String or Object} mark
    * @return {Node} node
    */
 
@@ -216,33 +217,28 @@ const Transforms = {
   },
 
   /**
-   * Insert a block `node` at `range`.
+   * Insert a `block` node at `range`.
    *
    * @param {Selection} range
-   * @param {Node} node
+   * @param {Block or String or Object} block
    * @return {Node} node
    */
 
-  insertBlockAtRange(range, node) {
-    let doc = this
+  insertBlockAtRange(range, block) {
+    block = normalizeBlock(block)
+    let node = this
 
     // If expanded, delete the range first.
     if (range.isExpanded) {
-      doc = doc.deleteAtRange(range)
+      node = node.deleteAtRange(range)
       range = range.collapseToStart()
     }
 
-    // Allow for passing just a type string.
-    if (typeof node == 'string') node = { type: node }
-
-    // Allow for passing a plain object of properties.
-    node = Block.create(node)
-
     const { startKey, startOffset } = range
-    let startBlock = doc.getClosestBlock(startKey)
-    let parent = doc.getParent(startBlock)
-    let nodes = Block.createList([node])
-    const isParent = parent == doc
+    let startBlock = node.getClosestBlock(startKey)
+    let parent = node.getParent(startBlock)
+    let nodes = Block.createList([block])
+    const isParent = parent == node
 
     // If the start block is void, insert after it.
     if (startBlock.isVoid) {
@@ -268,21 +264,21 @@ const Transforms = {
 
     // Otherwise, split the block and insert between.
     else {
-      doc = doc.splitBlockAtRange(range)
-      parent = doc.getParent(startBlock)
-      startBlock = doc.getClosestBlock(startKey)
+      node = node.splitBlockAtRange(range)
+      parent = node.getParent(startBlock)
+      startBlock = node.getClosestBlock(startKey)
       nodes = parent.nodes.takeUntil(n => n == startBlock)
         .push(startBlock)
-        .push(node)
+        .push(block)
         .concat(parent.nodes.skipUntil(n => n == startBlock).rest())
       parent = parent.merge({ nodes })
     }
 
-    doc = isParent
+    node = isParent
       ? parent
-      : doc.updateDescendant(parent)
+      : node.updateDescendant(parent)
 
-    return doc.normalize()
+    return node.normalize()
   },
 
   /**
@@ -385,51 +381,46 @@ const Transforms = {
   },
 
   /**
-   * Insert an inline `node` at `range`.
+   * Insert an `inline` node at `range`.
    *
    * @param {Selection} range
-   * @param {Node} node
+   * @param {Inline or String or Object} inline
    * @return {Node} node
    */
 
-  insertInlineAtRange(range, node) {
-    let doc = this
+  insertInlineAtRange(range, inline) {
+    inline = normalizeInline(inline)
+    let node = this
 
     // If expanded, delete the range first.
     if (range.isExpanded) {
-      doc = doc.deleteAtRange(range)
+      node = node.deleteAtRange(range)
       range = range.collapseToStart()
     }
 
     const { startKey, endKey, startOffset, endOffset } = range
 
     // If the range is inside a void, abort.
-    const block = doc.getClosestBlock(startKey)
-    if (block && block.isVoid) return doc
+    const startBlock = node.getClosestBlock(startKey)
+    if (startBlock && startBlock.isVoid) return node
 
-    const inline = doc.getClosestInline(startKey)
-    if (inline && inline.isVoid) return doc
-
-    // Allow for passing a type string.
-    if (typeof node == 'string') node = { type: node }
-
-    // Allow for passing a plain object of properties.
-    node = Inline.create(node)
+    const startInline = node.getClosestInline(startKey)
+    if (startInline && startInline.isVoid) return node
 
     // Split the text nodes at the cursor.
-    doc = doc.splitTextAtRange(range)
+    node = node.splitTextAtRange(range)
 
-    // Insert the node between the split text nodes.
-    const startText = doc.getDescendant(startKey)
-    let parent = doc.getParent(startKey)
+    // Insert the inline between the split text nodes.
+    const startText = node.getDescendant(startKey)
+    let parent = node.getParent(startKey)
     const nodes = parent.nodes.takeUntil(n => n == startText)
       .push(startText)
-      .push(node)
+      .push(inline)
       .concat(parent.nodes.skipUntil(n => n == startText).rest())
 
     parent = parent.merge({ nodes })
-    doc = doc.updateDescendant(parent)
-    return doc.normalize()
+    node = node.updateDescendant(parent)
+    return node.normalize()
   },
 
   /**
@@ -521,20 +512,10 @@ const Transforms = {
    */
 
   setBlockAtRange(range, properties = {}) {
+    properties = normalizeProperties(properties)
     let node = this
-
-    // Allow for properties to be a string `type` for convenience.
-    if (typeof properties == 'string') {
-      properties = { type: properties }
-    }
-    if (properties.data) {
-        properties.data = Data.create(properties.data)
-    } else {
-        delete properties.data
-    }
-
-    // Update each of the blocks.
     const blocks = node.getBlocksAtRange(range)
+
     blocks.forEach((block) => {
       block = block.merge(properties)
       node = node.updateDescendant(block)
@@ -552,17 +533,11 @@ const Transforms = {
    */
 
   setInlineAtRange(range, properties = {}) {
+    properties = normalizeProperties(properties)
     let node = this
-
-    // Allow for properties to be a string `type` for convenience.
-    if (typeof properties == 'string') {
-      properties = { type: properties }
-    }
-
-    // Update each of the inlines.
     const inlines = node.getInlinesAtRange(range)
+
     inlines.forEach((inline) => {
-      if (properties.data) properties.data = Data.create(properties.data)
       inline = inline.merge(properties)
       node = node.updateDescendant(inline)
     })
@@ -579,15 +554,9 @@ const Transforms = {
    */
 
   setNodeByKey(key, properties) {
+    properties = normalizeProperties(properties)
     let node = this
     let descendant = node.assertDescendant(key)
-
-    // Allow for properties to be a string `type` for convenience.
-    if (typeof properties == 'string') properties = { type: properties }
-
-    // Ensure that `data` is immutable.
-    if (properties.data) properties.data = Data.create(properties.data)
-
     descendant = descendant.merge(properties)
     node = node.updateDescendant(descendant)
     return node
@@ -1093,13 +1062,103 @@ function isInRange(index, text, range) {
  */
 
 function normalizeMark(mark) {
-  if (typeof mark == 'string') {
-    return Mark.create({ type: mark })
-  } else {
-    return Mark.create(mark)
+  if (mark instanceof Mark) return mark
+
+  const type = typeOf(mark)
+
+  switch (type) {
+    case 'string':
+    case 'object': {
+      return Mark.create(normalizeProperties(mark))
+    }
+    default: {
+      throw new Error(`A \`mark\` argument must be a mark, an object or a string, but you passed: "${type}".`)
+    }
   }
 }
 
+/**
+ * Normalize a `block` argument, which can be a string or plain object too.
+ *
+ * @param {Block or String or Object} block
+ * @return {Block}
+ */
+
+function normalizeBlock(block) {
+  if (block instanceof Block) return block
+
+  const type = typeOf(block)
+
+  switch (type) {
+    case 'string':
+    case 'object': {
+      return Block.create(normalizeProperties(block))
+    }
+    default: {
+      throw new Error(`A \`block\` argument must be a block, an object or a string, but you passed: "${type}".`)
+    }
+  }
+}
+
+/**
+ * Normalize an `inline` argument, which can be a string or plain object too.
+ *
+ * @param {Inline or String or Object} inline
+ * @return {Inline}
+ */
+
+function normalizeInline(inline) {
+  if (inline instanceof Inline) return inline
+
+  const type = typeOf(inline)
+
+  switch (type) {
+    case 'string':
+    case 'object': {
+      return Inline.create(normalizeProperties(inline))
+    }
+    default: {
+      throw new Error(`An \`inline\` argument must be an inline, an object or a string, but you passed: "${type}".`)
+    }
+  }
+}
+
+/**
+ * Normalize the `properties` of a node or mark, which can be either a type
+ * string or a dictionary of properties. If it's a dictionary, `data` is
+ * optional and shouldn't be set if null or undefined.
+ *
+ * @param {String or Object} properties
+ * @return {Object}
+ */
+
+function normalizeProperties(properties = {}) {
+  const ret = {}
+  const type = typeOf(properties)
+
+  switch (type) {
+    case 'string': {
+      ret.type = properties
+      break
+    }
+    case 'object': {
+      for (const key in properties) {
+        if (key == 'data') {
+          if (properties[key] != null) ret[key] = Data.create(properties[key])
+        } else {
+          ret[key] = properties[key]
+        }
+      }
+      break
+    }
+    default: {
+      throw new Error(`A \`properties\` argument must be an object or a string, but you passed: "${type}".`)
+    }
+  }
+
+  return ret
+}
+
 /**
  * Export.
  */
diff --git a/package.json b/package.json
index c845f1e82..8c8ced673 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "keycode": "^2.1.2",
     "lodash": "^4.13.1",
     "react-portal": "^2.2.0",
+    "type-of": "^2.0.1",
     "ua-parser-js": "^0.7.10",
     "uid": "0.0.2"
   },