diff --git a/packages/pretty-format/src/index.js b/packages/pretty-format/src/index.js
index b1c5e33425de..68de55f1d0ad 100644
--- a/packages/pretty-format/src/index.js
+++ b/packages/pretty-format/src/index.js
@@ -875,7 +875,13 @@ function prettyFormat(val: any, initialOptions?: InitialOptions): string {
     opts = normalizeOptions(initialOptions);
   }
 
-  const colors: Colors = {};
+  const colors: Colors = {
+    comment: {close: '', open: ''},
+    content: {close: '', open: ''},
+    prop: {close: '', open: ''},
+    tag: {close: '', open: ''},
+    value: {close: '', open: ''},
+  };
   Object.keys(opts.theme).forEach(key => {
     if (opts.highlight) {
       const color = (colors[key] = style[opts.theme[key]]);
@@ -888,8 +894,6 @@ function prettyFormat(val: any, initialOptions?: InitialOptions): string {
           `pretty-format: Option "theme" has a key "${key}" whose value "${opts.theme[key]}" is undefined in ansi-styles.`,
         );
       }
-    } else {
-      colors[key] = {close: '', open: ''};
     }
   });
 
diff --git a/packages/pretty-format/src/plugins/HTMLElement.js b/packages/pretty-format/src/plugins/HTMLElement.js
index 6f0424412e13..8e8591248444 100644
--- a/packages/pretty-format/src/plugins/HTMLElement.js
+++ b/packages/pretty-format/src/plugins/HTMLElement.js
@@ -13,6 +13,28 @@
 import type {Colors, Indent, Options, Print, Plugin} from 'types/PrettyFormat';
 
 const escapeHTML = require('./lib/escapeHTML');
+
+type Attribute = {
+  name: string,
+  value: string,
+};
+
+type HTMLElement = {
+  attributes: Array<Attribute>,
+  childNodes: Array<HTMLElement | HTMLText | HTMLComment>,
+  nodeType: 1,
+  tagName: string,
+};
+type HTMLText = {
+  data: string,
+  nodeType: 3,
+};
+
+type HTMLComment = {
+  data: string,
+  nodeType: 8,
+};
+
 const HTML_ELEMENT_REGEXP = /(HTML\w*?Element)|Text|Comment/;
 const test = isHTMLElement;
 
@@ -41,7 +63,7 @@ function printChildren(flatChildren, print, indent, colors, opts) {
     .join(opts.edgeSpacing);
 }
 
-function printAttributes(attributes, indent, colors, opts) {
+function printAttributes(attributes: Array<Attribute>, indent, colors, opts) {
   return attributes
     .sort()
     .map(attribute => {
@@ -57,17 +79,15 @@ function printAttributes(attributes, indent, colors, opts) {
 }
 
 const print = (
-  element: HTMLElement | Text | Comment,
+  element: HTMLElement | HTMLText | HTMLComment,
   print: Print,
   indent: Indent,
   opts: Options,
   colors: Colors,
 ): string => {
-  if (element instanceof Text) {
+  if (element.nodeType === 3) {
     return element.data;
-  }
-
-  if (element instanceof Comment) {
+  } else if (element.nodeType === 8) {
     return (
       colors.comment.open + '<!--' + element.data + '-->' + colors.comment.close
     );
diff --git a/types/PrettyFormat.js b/types/PrettyFormat.js
index 02c52b811428..fde835d83f4c 100644
--- a/types/PrettyFormat.js
+++ b/types/PrettyFormat.js
@@ -9,7 +9,13 @@
  */
 'use strict';
 
-export type Colors = Object;
+export type Colors = {
+  comment: {close: string, open: string},
+  content: {close: string, open: string},
+  prop: {close: string, open: string},
+  tag: {close: string, open: string},
+  value: {close: string, open: string},
+};
 export type Indent = string => string;
 export type Refs = Array<any>;
 export type Print = any => string;