diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index 2de75e31e..ccfa138e9 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -635,7 +635,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
                 assert(isName(type),
                   'XObject should have a Name subtype');
 
-                if ('Form' == type.name) {
+                if (type.name === 'Form') {
                   stateManager.save();
                   return self.buildFormXObject(resources, xobj, null,
                                                operatorList,
@@ -644,11 +644,16 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
                       stateManager.restore();
                       next(resolve, reject);
                     }, reject);
-                } else if ('Image' == type.name) {
+                } else if (type.name === 'Image') {
                   self.buildPaintImageXObject(resources, xobj, false,
                     operatorList, name, imageCache);
                   args = [];
                   continue;
+                } else if (type.name === 'PS') {
+                  // PostScript XObjects are unused when viewing documents.
+                  // See section 4.7.1 of Adobe's PDF reference.
+                  info('Ignored XObject subtype PS');
+                  continue;
                 } else {
                   error('Unhandled XObject subtype ' + type.name);
                 }