diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index 46c45fd58..91d7b610d 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -21,7 +21,7 @@ import {
 } from '../shared/util';
 import { CMapFactory, IdentityCMap } from './cmap';
 import {
-  Cmd, Dict, EOF, isDict, isName, isRef, isStream, Name
+  Cmd, Dict, EOF, isDict, isName, isRef, isStream, Name, Ref
 } from './primitives';
 import {
   ErrorFont, Font, FontFlags, getFontType, IdentityToUnicodeMap, ToUnicodeMap
@@ -180,7 +180,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
     },
 
     hasBlendModes: function PartialEvaluator_hasBlendModes(resources) {
-      if (!isDict(resources)) {
+      if (!(resources instanceof Dict)) {
         return false;
       }
 
@@ -191,33 +191,44 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
 
       var nodes = [resources], xref = this.xref;
       while (nodes.length) {
-        var key, i, ii;
         var node = nodes.shift();
         // First check the current resources for blend modes.
         var graphicStates = node.get('ExtGState');
-        if (isDict(graphicStates)) {
+        if (graphicStates instanceof Dict) {
           var graphicStatesKeys = graphicStates.getKeys();
-          for (i = 0, ii = graphicStatesKeys.length; i < ii; i++) {
-            key = graphicStatesKeys[i];
+          for (let i = 0, ii = graphicStatesKeys.length; i < ii; i++) {
+            const key = graphicStatesKeys[i];
 
-            var graphicState = graphicStates.get(key);
+            let graphicState = graphicStates.getRaw(key);
+            if (graphicState instanceof Ref) {
+              if (processed[graphicState.toString()]) {
+                continue; // The ExtGState has already been processed.
+              }
+              graphicState = xref.fetch(graphicState);
+            }
+            if (!(graphicState instanceof Dict)) {
+              continue;
+            }
+            if (graphicState.objId) {
+              processed[graphicState.objId] = true;
+            }
             var bm = graphicState.get('BM');
-            if (isName(bm) && bm.name !== 'Normal') {
+            if ((bm instanceof Name) && bm.name !== 'Normal') {
               return true;
             }
           }
         }
         // Descend into the XObjects to look for more resources and blend modes.
         var xObjects = node.get('XObject');
-        if (!isDict(xObjects)) {
+        if (!(xObjects instanceof Dict)) {
           continue;
         }
         var xObjectsKeys = xObjects.getKeys();
-        for (i = 0, ii = xObjectsKeys.length; i < ii; i++) {
-          key = xObjectsKeys[i];
+        for (let i = 0, ii = xObjectsKeys.length; i < ii; i++) {
+          const key = xObjectsKeys[i];
 
           var xObject = xObjects.getRaw(key);
-          if (isRef(xObject)) {
+          if (xObject instanceof Ref) {
             if (processed[xObject.toString()]) {
               // The XObject has already been processed, and by avoiding a
               // redundant `xref.fetch` we can *significantly* reduce the load
@@ -231,14 +242,13 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
           }
           if (xObject.dict.objId) {
             if (processed[xObject.dict.objId]) {
-              // stream has objId and is processed already
-              continue;
+              continue; // Stream has objId and was processed already.
             }
             processed[xObject.dict.objId] = true;
           }
           var xResources = xObject.dict.get('Resources');
           // Checking objId to detect an infinite loop.
-          if (isDict(xResources) &&
+          if ((xResources instanceof Dict) &&
               (!xResources.objId || !processed[xResources.objId])) {
             nodes.push(xResources);
             if (xResources.objId) {