diff --git a/src/plugins/core.js b/src/plugins/core.js
index c1c1ec93c..b3109f985 100644
--- a/src/plugins/core.js
+++ b/src/plugins/core.js
@@ -1,7 +1,9 @@
 
 import Base64 from '../serializers/base-64'
 import Content from '../components/content'
+import Block from '../models/block'
 import Character from '../models/character'
+import Inline from '../models/inline'
 import Debug from 'debug'
 import getPoint from '../utils/get-point'
 import Placeholder from '../components/placeholder'
@@ -381,11 +383,20 @@ function Plugin(options = {}) {
 
     if (isInternal) transform.delete()
 
-    return transform
-      .select(target)
-      .insertBlock(node)
-      .removeNodeByKey(node.key)
-      .apply()
+    if (Block.isBlock(node)) {
+      return transform
+        .select(target)
+        .insertBlock(node)
+        .removeNodeByKey(node.key)
+        .apply()
+    }
+    if (Inline.isInline(node)) {
+      return transform
+        .select(target)
+        .insertInline(node)
+        .removeNodeByKey(node.key)
+        .apply()
+    }
   }
 
   /**
diff --git a/src/utils/normalize.js b/src/utils/normalize.js
index 89d16dab8..83b5a07a0 100644
--- a/src/utils/normalize.js
+++ b/src/utils/normalize.js
@@ -18,12 +18,20 @@ import typeOf from 'type-of'
 
 function block(value) {
   if (Block.isBlock(value)) return value
+  if (
+    Inline.isInline(value) ||
+    Mark.isMark(value) ||
+    Text.isText(value) ||
+    Selection.isSelection(value)
+  ) {
+    throw new Error(`Invalid \`block\` argument! It must be a block, an object, or a string. You passed: "${value}".`)
+  }
+
 
   switch (typeOf(value)) {
     case 'string':
     case 'object':
       return Block.create(nodeProperties(value))
-
     default:
       throw new Error(`Invalid \`block\` argument! It must be a block, an object, or a string. You passed: "${value}".`)
   }
@@ -38,12 +46,19 @@ function block(value) {
 
 function inline(value) {
   if (Inline.isInline(value)) return value
+  if (
+    Block.isBlock(value) ||
+    Mark.isMark(value) ||
+    Text.isText(value) ||
+    Selection.isSelection(value)
+  ) {
+    throw new Error(`Invalid \`inline\` argument! It must be an inline, an object, or a string. You passed: "${value}".`)
+  }
 
   switch (typeOf(value)) {
     case 'string':
     case 'object':
       return Inline.create(nodeProperties(value))
-
     default:
       throw new Error(`Invalid \`inline\` argument! It must be an inline, an object, or a string. You passed: "${value}".`)
   }
@@ -60,10 +75,14 @@ function key(value) {
   if (typeOf(value) == 'string') return value
 
   warn('An object was passed to a Node method instead of a `key` string. This was previously supported, but is being deprecated because it can have a negative impact on performance. The object in question was:', value)
-  if (Block.isBlock(value)) return value.key
-  if (Document.isDocument(value)) return value.key
-  if (Inline.isInline(value)) return value.key
-  if (Text.isText(value)) return value.key
+  if (
+    Block.isBlock(value) ||
+    Document.isDocument(value) ||
+    Inline.isInline(value) ||
+    Text.isText(value)
+  ) {
+    return value.key
+  }
 
   throw new Error(`Invalid \`key\` argument! It must be either a block, an inline, a text, or a string. You passed: "${value}".`)
 }
@@ -77,12 +96,19 @@ function key(value) {
 
 function mark(value) {
   if (Mark.isMark(value)) return value
+  if (
+    Block.isBlock(value) ||
+    Inline.isInline(value) ||
+    Text.isText(value) ||
+    Selection.isSelection(value)
+  ) {
+    throw new Error(`Invalid \`mark\` argument! It must be a mark, an object, or a string. You passed: "${value}".`)
+  }
 
   switch (typeOf(value)) {
     case 'string':
     case 'object':
       return Mark.create(markProperties(value))
-
     default:
       throw new Error(`Invalid \`mark\` argument! It must be a mark, an object, or a string. You passed: "${value}".`)
   }
@@ -107,6 +133,8 @@ function markProperties(value = {}) {
       for (const k in value) {
         if (k == 'data') {
           if (value[k] !== undefined) ret[k] = Data.create(value[k])
+        } else if (k.startsWith('@@__SLATE')) {
+          return
         } else {
           ret[k] = value[k]
         }
@@ -140,6 +168,8 @@ function nodeProperties(value = {}) {
       for (const k in value) {
         if (k == 'data') {
           if (value[k] !== undefined) ret[k] = Data.create(value[k])
+        } else if (k.startsWith('@@__SLATE')) {
+          return
         } else {
           ret[k] = value[k]
         }
@@ -162,11 +192,18 @@ function nodeProperties(value = {}) {
 
 function selection(value) {
   if (Selection.isSelection(value)) return value
+  if (
+    Mark.isMark(value) ||
+    Block.isBlock(value) ||
+    Inline.isInline(value) ||
+    Text.isText(value)
+  ) {
+    throw new Error(`Invalid \`selection\` argument! It must be a selection or an object. You passed: "${value}".`)``
+  }
 
   switch (typeOf(value)) {
     case 'object':
       return Selection.create(value)
-
     default:
       throw new Error(`Invalid \`selection\` argument! It must be a selection or an object. You passed: "${value}".`)
   }
@@ -192,7 +229,6 @@ function selectionProperties(value = {}) {
       if (value.isFocused !== undefined) ret.isFocused = !!value.isFocused
       if (value.marks !== undefined) ret.marks = value.marks
       break
-
     default:
       throw new Error(`Invalid selection \`properties\` argument! It must be an object or a selection. You passed: "${value}".`)
   }