diff --git a/src/core/annotation.js b/src/core/annotation.js
index 4fca1e83b..7d807419b 100644
--- a/src/core/annotation.js
+++ b/src/core/annotation.js
@@ -15,8 +15,7 @@
 
 import {
   AnnotationBorderStyleType, AnnotationFieldFlag, AnnotationFlag,
-  AnnotationType, isArray, isInt, OPS, stringToBytes, stringToPDFString, Util,
-  warn
+  AnnotationType, isArray, OPS, stringToBytes, stringToPDFString, Util, warn
 } from '../shared/util';
 import { Catalog, FileSpec, ObjectLoader } from './obj';
 import { Dict, isDict, isName, isRef, isStream } from './primitives';
@@ -212,7 +211,7 @@ class Annotation {
    * @see {@link shared/util.js}
    */
   setFlags(flags) {
-    this.flags = (isInt(flags) && flags > 0) ? flags : 0;
+    this.flags = (Number.isInteger(flags) && flags > 0) ? flags : 0;
   }
 
   /**
@@ -575,7 +574,7 @@ class WidgetAnnotation extends Annotation {
     this.fieldResources = Util.getInheritableProperty(dict, 'DR') || Dict.empty;
 
     data.fieldFlags = Util.getInheritableProperty(dict, 'Ff');
-    if (!isInt(data.fieldFlags) || data.fieldFlags < 0) {
+    if (!Number.isInteger(data.fieldFlags) || data.fieldFlags < 0) {
       data.fieldFlags = 0;
     }
 
@@ -666,14 +665,14 @@ class TextWidgetAnnotation extends WidgetAnnotation {
 
     // Determine the alignment of text in the field.
     let alignment = Util.getInheritableProperty(params.dict, 'Q');
-    if (!isInt(alignment) || alignment < 0 || alignment > 2) {
+    if (!Number.isInteger(alignment) || alignment < 0 || alignment > 2) {
       alignment = null;
     }
     this.data.textAlignment = alignment;
 
     // Determine the maximum length of text in the field.
     let maximumLength = Util.getInheritableProperty(params.dict, 'MaxLen');
-    if (!isInt(maximumLength) || maximumLength < 0) {
+    if (!Number.isInteger(maximumLength) || maximumLength < 0) {
       maximumLength = null;
     }
     this.data.maxLen = maximumLength;
diff --git a/src/core/chunked_stream.js b/src/core/chunked_stream.js
index d670af4d1..0c754488f 100644
--- a/src/core/chunked_stream.js
+++ b/src/core/chunked_stream.js
@@ -14,7 +14,7 @@
  */
 
 import {
-  arrayByteLength, arraysToBytes, createPromiseCapability, isEmptyObj, isInt,
+  arrayByteLength, arraysToBytes, createPromiseCapability, isEmptyObj,
   MissingDataException
 } from '../shared/util';
 
@@ -518,7 +518,7 @@ var ChunkedStreamManager = (function ChunkedStreamManagerClosure() {
         } else {
           nextEmptyChunk = this.stream.nextEmptyChunk(endChunk);
         }
-        if (isInt(nextEmptyChunk)) {
+        if (Number.isInteger(nextEmptyChunk)) {
           this._requestChunks([nextEmptyChunk]);
         }
       }
diff --git a/src/core/cmap.js b/src/core/cmap.js
index b15ff9596..f6b6e8679 100644
--- a/src/core/cmap.js
+++ b/src/core/cmap.js
@@ -14,8 +14,7 @@
  */
 
 import {
-  CMapCompressionType, FormatError, isInt, isString, MissingDataException, Util,
-  warn
+  CMapCompressionType, FormatError, isString, MissingDataException, Util, warn
 } from '../shared/util';
 import { isCmd, isEOF, isName, isStream } from './primitives';
 import { Lexer } from './parser';
@@ -370,11 +369,11 @@ var IdentityCMap = (function IdentityCMapClosure() {
     },
 
     lookup(code) {
-      return (isInt(code) && code <= 0xffff) ? code : undefined;
+      return (Number.isInteger(code) && code <= 0xffff) ? code : undefined;
     },
 
     contains(code) {
-      return isInt(code) && code <= 0xffff;
+      return Number.isInteger(code) && code <= 0xffff;
     },
 
     forEach(callback) {
@@ -384,7 +383,7 @@ var IdentityCMap = (function IdentityCMapClosure() {
     },
 
     charCodeOf(value) {
-      return (isInt(value) && value <= 0xffff) ? value : -1;
+      return (Number.isInteger(value) && value <= 0xffff) ? value : -1;
     },
 
     getMap() {
@@ -718,7 +717,7 @@ var CMapFactory = (function CMapFactoryClosure() {
   }
 
   function expectInt(obj) {
-    if (!isInt(obj)) {
+    if (!Number.isInteger(obj)) {
       throw new FormatError('Malformed CMap: expected int.');
     }
   }
@@ -757,8 +756,8 @@ var CMapFactory = (function CMapFactoryClosure() {
       expectString(obj);
       var high = strToInt(obj);
       obj = lexer.getObj();
-      if (isInt(obj) || isString(obj)) {
-        var dstLow = isInt(obj) ? String.fromCharCode(obj) : obj;
+      if (Number.isInteger(obj) || isString(obj)) {
+        var dstLow = Number.isInteger(obj) ? String.fromCharCode(obj) : obj;
         cMap.mapBfRange(low, high, dstLow);
       } else if (isCmd(obj, '[')) {
         obj = lexer.getObj();
@@ -839,7 +838,7 @@ var CMapFactory = (function CMapFactoryClosure() {
 
   function parseWMode(cMap, lexer) {
     var obj = lexer.getObj();
-    if (isInt(obj)) {
+    if (Number.isInteger(obj)) {
       cMap.vertical = !!obj;
     }
   }
diff --git a/src/core/crypto.js b/src/core/crypto.js
index 687504f1f..e87c3e10e 100644
--- a/src/core/crypto.js
+++ b/src/core/crypto.js
@@ -14,7 +14,7 @@
  */
 
 import {
-  bytesToString, FormatError, isInt, PasswordException, PasswordResponses,
+  bytesToString, FormatError, PasswordException, PasswordResponses,
   stringToBytes, utf8StringToString, warn
 } from '../shared/util';
 import { isDict, isName, Name } from './primitives';
@@ -1862,9 +1862,9 @@ var CipherTransformFactory = (function CipherTransformFactoryClosure() {
     }
     this.dict = dict;
     var algorithm = dict.get('V');
-    if (!isInt(algorithm) ||
+    if (!Number.isInteger(algorithm) ||
         (algorithm !== 1 && algorithm !== 2 && algorithm !== 4 &&
-        algorithm !== 5)) {
+         algorithm !== 5)) {
       throw new FormatError('unsupported encryption algorithm');
     }
     this.algorithm = algorithm;
@@ -1890,7 +1890,7 @@ var CipherTransformFactory = (function CipherTransformFactoryClosure() {
         }
       }
     }
-    if (!isInt(keyLength) ||
+    if (!Number.isInteger(keyLength) ||
         keyLength < 40 || (keyLength % 8) !== 0) {
       throw new FormatError('invalid key length');
     }
diff --git a/src/core/fonts.js b/src/core/fonts.js
index 7f62283ea..65ba5ef37 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -15,8 +15,7 @@
 
 import {
   bytesToString, FONT_IDENTITY_MATRIX, FontType, FormatError, info, isArray,
-  isInt, isNum, isSpace, MissingDataException, readUint32, shadow, string32,
-  warn
+  isNum, isSpace, MissingDataException, readUint32, shadow, string32, warn
 } from '../shared/util';
 import {
   CFF, CFFCharset, CFFCompiler, CFFHeader, CFFIndex, CFFParser, CFFPrivateDict,
@@ -291,7 +290,8 @@ var IdentityToUnicodeMap = (function IdentityToUnicodeMapClosure() {
     },
 
     charCodeOf(v) {
-      return (isInt(v) && v >= this.firstChar && v <= this.lastChar) ? v : -1;
+      return (Number.isInteger(v) &&
+              v >= this.firstChar && v <= this.lastChar) ? v : -1;
     },
 
     amend(map) {
diff --git a/src/core/obj.js b/src/core/obj.js
index 841da2cc3..eecf42e7d 100644
--- a/src/core/obj.js
+++ b/src/core/obj.js
@@ -15,9 +15,8 @@
 
 import {
   bytesToString, createPromiseCapability, createValidAbsoluteUrl, FormatError,
-  info, InvalidPDFException, isArray, isBool, isInt, isString,
-  MissingDataException, shadow, stringToPDFString, stringToUTF8String, Util,
-  warn, XRefParseException
+  info, InvalidPDFException, isArray, isBool, isString, MissingDataException,
+  shadow, stringToPDFString, stringToUTF8String, Util, warn, XRefParseException
 } from '../shared/util';
 import {
   Dict, isCmd, isDict, isName, isRef, isRefsEqual, isStream, Ref, RefSet,
@@ -169,7 +168,7 @@ var Catalog = (function CatalogClosure() {
     },
     get numPages() {
       var obj = this.toplevelPagesDict.get('Count');
-      if (!isInt(obj)) {
+      if (!Number.isInteger(obj)) {
         throw new FormatError(
           'page count in top level pages object is not an integer');
       }
@@ -286,7 +285,7 @@ var Catalog = (function CatalogClosure() {
           prefix = p ? stringToPDFString(p) : '';
 
           var st = labelDict.get('St');
-          if (st && !(isInt(st) && st >= 1)) {
+          if (st && !(Number.isInteger(st) && st >= 1)) {
             throw new FormatError('Invalid start in PageLabel dictionary.');
           }
           currentIndex = st || 1;
@@ -912,7 +911,7 @@ var XRef = (function XRefClosure() {
 
         var first = tableState.firstEntryNum;
         var count = tableState.entryCount;
-        if (!isInt(first) || !isInt(count)) {
+        if (!Number.isInteger(first) || !Number.isInteger(count)) {
           throw new FormatError(
             'Invalid XRef table: wrong types in subsection header');
         }
@@ -935,7 +934,7 @@ var XRef = (function XRefClosure() {
           }
 
           // Validate entry obj
-          if (!isInt(entry.offset) || !isInt(entry.gen) ||
+          if (!Number.isInteger(entry.offset) || !Number.isInteger(entry.gen) ||
               !(entry.free || entry.uncompressed)) {
             throw new FormatError(
               `Invalid entry in XRef subsection: ${first}, ${count}`);
@@ -1007,12 +1006,13 @@ var XRef = (function XRefClosure() {
         var first = entryRanges[0];
         var n = entryRanges[1];
 
-        if (!isInt(first) || !isInt(n)) {
+        if (!Number.isInteger(first) || !Number.isInteger(n)) {
           throw new FormatError(
             `Invalid XRef range fields: ${first}, ${n}`);
         }
-        if (!isInt(typeFieldWidth) || !isInt(offsetFieldWidth) ||
-            !isInt(generationFieldWidth)) {
+        if (!Number.isInteger(typeFieldWidth) ||
+            !Number.isInteger(offsetFieldWidth) ||
+            !Number.isInteger(generationFieldWidth)) {
           throw new FormatError(
             `Invalid XRef entry fields length: ${first}, ${n}`);
         }
@@ -1229,7 +1229,7 @@ var XRef = (function XRefClosure() {
 
             // Recursively get other XRefs 'XRefStm', if any
             obj = dict.get('XRefStm');
-            if (isInt(obj)) {
+            if (Number.isInteger(obj)) {
               var pos = obj;
               // ignore previously loaded xref streams
               // (possible infinite recursion)
@@ -1238,9 +1238,9 @@ var XRef = (function XRefClosure() {
                 this.startXRefQueue.push(pos);
               }
             }
-          } else if (isInt(obj)) {
+          } else if (Number.isInteger(obj)) {
             // Parse in-stream XRef
-            if (!isInt(parser.getObj()) ||
+            if (!Number.isInteger(parser.getObj()) ||
                 !isCmd(parser.getObj(), 'obj') ||
                 !isStream(obj = parser.getObj())) {
               throw new FormatError('Invalid XRef stream');
@@ -1258,7 +1258,7 @@ var XRef = (function XRefClosure() {
 
           // Recursively get previous dictionary, if any
           obj = dict.get('Prev');
-          if (isInt(obj)) {
+          if (Number.isInteger(obj)) {
             this.startXRefQueue.push(obj);
           } else if (isRef(obj)) {
             // The spec says Prev must not be a reference, i.e. "/Prev NNN"
@@ -1386,7 +1386,7 @@ var XRef = (function XRefClosure() {
       }
       var first = stream.dict.get('First');
       var n = stream.dict.get('N');
-      if (!isInt(first) || !isInt(n)) {
+      if (!Number.isInteger(first) || !Number.isInteger(n)) {
         throw new FormatError(
           'invalid first and n parameters for ObjStm stream');
       }
@@ -1396,13 +1396,13 @@ var XRef = (function XRefClosure() {
       // read the object numbers to populate cache
       for (i = 0; i < n; ++i) {
         num = parser.getObj();
-        if (!isInt(num)) {
+        if (!Number.isInteger(num)) {
           throw new FormatError(
             `invalid object number in the ObjStm stream: ${num}`);
         }
         nums.push(num);
         var offset = parser.getObj();
-        if (!isInt(offset)) {
+        if (!Number.isInteger(offset)) {
           throw new FormatError(
             `invalid object offset in the ObjStm stream: ${offset}`);
         }
diff --git a/src/core/parser.js b/src/core/parser.js
index 954bec8ba..2d3be78dc 100644
--- a/src/core/parser.js
+++ b/src/core/parser.js
@@ -18,8 +18,8 @@ import {
   JpegStream, JpxStream, LZWStream, NullStream, PredictorStream, RunLengthStream
 } from './stream';
 import {
-  assert, FormatError, info, isArray, isInt, isNum, isString,
-  MissingDataException, StreamType, warn
+  assert, FormatError, info, isArray, isNum, isString, MissingDataException,
+  StreamType, warn
 } from '../shared/util';
 import {
   Cmd, Dict, EOF, isCmd, isDict, isEOF, isName, Name, Ref
@@ -121,9 +121,9 @@ var Parser = (function ParserClosure() {
         }
       }
 
-      if (isInt(buf1)) { // indirect reference or integer
+      if (Number.isInteger(buf1)) { // indirect reference or integer
         var num = buf1;
-        if (isInt(this.buf1) && isCmd(this.buf2, 'R')) {
+        if (Number.isInteger(this.buf1) && isCmd(this.buf2, 'R')) {
           var ref = new Ref(num, this.buf1);
           this.shift();
           this.shift();
@@ -456,7 +456,7 @@ var Parser = (function ParserClosure() {
 
       // get length
       var length = dict.get('Length');
-      if (!isInt(length)) {
+      if (!Number.isInteger(length)) {
         info('Bad ' + length + ' attribute in stream');
         length = 0;
       }
@@ -1069,7 +1069,7 @@ var Linearization = {
   create: function LinearizationCreate(stream) {
     function getInt(name, allowZeroValue) {
       var obj = linDict.get(name);
-      if (isInt(obj) && (allowZeroValue ? obj >= 0 : obj > 0)) {
+      if (Number.isInteger(obj) && (allowZeroValue ? obj >= 0 : obj > 0)) {
         return obj;
       }
       throw new Error('The "' + name + '" parameter in the linearization ' +
@@ -1080,7 +1080,7 @@ var Linearization = {
       if (isArray(hints) &&
           ((hintsLength = hints.length) === 2 || hintsLength === 4)) {
         for (var index = 0; index < hintsLength; index++) {
-          if (!(isInt(item = hints[index]) && item > 0)) {
+          if (!(Number.isInteger(item = hints[index]) && item > 0)) {
             throw new Error('Hint (' + index +
                             ') in the linearization dictionary is invalid.');
           }
@@ -1095,7 +1095,8 @@ var Linearization = {
     var obj3 = parser.getObj();
     var linDict = parser.getObj();
     var obj, length;
-    if (!(isInt(obj1) && isInt(obj2) && isCmd(obj3, 'obj') && isDict(linDict) &&
+    if (!(Number.isInteger(obj1) && Number.isInteger(obj2) &&
+          isCmd(obj3, 'obj') && isDict(linDict) &&
           isNum(obj = linDict.get('Linearized')) && obj > 0)) {
       return null; // No valid linearization dictionary found.
     } else if ((length = getInt('L')) !== stream.length) {
diff --git a/src/core/stream.js b/src/core/stream.js
index 5aa78c392..10e88ea90 100644
--- a/src/core/stream.js
+++ b/src/core/stream.js
@@ -14,7 +14,7 @@
  */
 
 import {
-  createObjectURL, FormatError, info, isArray, isInt, isSpace, shadow, Util
+  createObjectURL, FormatError, info, isArray, isSpace, shadow, Util
 } from '../shared/util';
 import { Dict, isDict, isStream } from './primitives';
 import { Jbig2Image } from './jbig2';
@@ -927,7 +927,7 @@ var JpegStream = (function JpegStreamClosure() {
     // Fetching the 'ColorTransform' entry, if it exists.
     if (isDict(this.params)) {
       var colorTransform = this.params.get('ColorTransform');
-      if (isInt(colorTransform)) {
+      if (Number.isInteger(colorTransform)) {
         jpegImage.colorTransform = colorTransform;
       }
     }
diff --git a/src/display/api.js b/src/display/api.js
index 3f4b5101f..ddd764d5f 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -15,11 +15,11 @@
 /* globals requirejs, __non_webpack_require__ */
 
 import {
-  assert, createPromiseCapability, deprecated, getVerbosityLevel,
-  info, InvalidPDFException, isArrayBuffer, isInt, isSameOrigin,
-  loadJpegStream, MessageHandler, MissingPDFException, NativeImageDecoding,
-  PageViewport, PasswordException, StatTimer, stringToBytes,
-  UnexpectedResponseException, UnknownErrorException, Util, warn
+  assert, createPromiseCapability, deprecated, getVerbosityLevel, info,
+  InvalidPDFException, isArrayBuffer, isSameOrigin, loadJpegStream,
+  MessageHandler, MissingPDFException, NativeImageDecoding, PageViewport,
+  PasswordException, StatTimer, stringToBytes, UnexpectedResponseException,
+  UnknownErrorException, Util, warn
 } from '../shared/util';
 import {
   DOMCanvasFactory, DOMCMapReaderFactory, getDefaultSetting,
@@ -1986,7 +1986,8 @@ var WorkerTransport = (function WorkerTransportClosure() {
     },
 
     getPage: function WorkerTransport_getPage(pageNumber, capability) {
-      if (!isInt(pageNumber) || pageNumber <= 0 || pageNumber > this.numPages) {
+      if (!Number.isInteger(pageNumber) ||
+          pageNumber <= 0 || pageNumber > this.numPages) {
         return Promise.reject(new Error('Invalid page request'));
       }
 
diff --git a/src/display/network_utils.js b/src/display/network_utils.js
index 5328b0c36..94e6b2fc9 100644
--- a/src/display/network_utils.js
+++ b/src/display/network_utils.js
@@ -13,7 +13,8 @@
  * limitations under the License.
  */
 
-import { assert, isInt, MissingPDFException, UnexpectedResponseException
+import {
+  assert, MissingPDFException, UnexpectedResponseException
 } from '../shared/util';
 
 function validateRangeRequestCapabilities({ getResponseHeader, isHttp,
@@ -35,17 +36,15 @@ function validateRangeRequestCapabilities({ getResponseHeader, isHttp,
     return returnValues;
   }
 
-  let length = getResponseHeader('Content-Length');
-  length = parseInt(length, 10);
-  if (!isInt(length)) {
+  let length = parseInt(getResponseHeader('Content-Length'), 10);
+  if (!Number.isInteger(length)) {
     return returnValues;
   }
 
   returnValues.suggestedLength = length;
   if (length <= 2 * rangeChunkSize) {
-    // The file size is smaller than the size of two chunks, so it does
-    // not make any sense to abort the request and retry with a range
-    // request.
+    // The file size is smaller than the size of two chunks, so it does not
+    // make any sense to abort the request and retry with a range request.
     return returnValues;
   }
 
diff --git a/src/shared/util.js b/src/shared/util.js
index 15b3f8ffc..adf109ed7 100644
--- a/src/shared/util.js
+++ b/src/shared/util.js
@@ -817,7 +817,7 @@ var Util = (function UtilClosure() {
    * @return {string} The resulting Roman number.
    */
   Util.toRoman = function Util_toRoman(number, lowerCase) {
-    assert(isInt(number) && number > 0,
+    assert(Number.isInteger(number) && number > 0,
            'The number should be a positive integer.');
     var pos, romanBuf = [];
     // Thousands
@@ -1075,10 +1075,6 @@ function isBool(v) {
   return typeof v === 'boolean';
 }
 
-function isInt(v) {
-  return typeof v === 'number' && ((v | 0) === v);
-}
-
 function isNum(v) {
   return typeof v === 'number';
 }
@@ -1703,7 +1699,6 @@ export {
   isArrayBuffer,
   isBool,
   isEmptyObj,
-  isInt,
   isNum,
   isString,
   isSpace,
diff --git a/test/unit/fonts_spec.js b/test/unit/fonts_spec.js
index c5e6e858e..483921a37 100644
--- a/test/unit/fonts_spec.js
+++ b/test/unit/fonts_spec.js
@@ -16,7 +16,6 @@
 import {
   PRIVATE_USE_OFFSET_END, PRIVATE_USE_OFFSET_START, ProblematicCharRanges
 } from '../../src/core/fonts';
-import { isInt } from '../../src/shared/util';
 
 /**
  * Used to validate the entries in `ProblematicCharRanges`, and to ensure that
@@ -41,7 +40,7 @@ var checkProblematicCharRanges = function checkProblematicCharRanges() {
       lower: ProblematicCharRanges[i],
       upper: ProblematicCharRanges[i + 1],
     };
-    if (!isInt(limits.lower) || !isInt(limits.upper)) {
+    if (!Number.isInteger(limits.lower) || !Number.isInteger(limits.upper)) {
       throw new Error('Range endpoints must be integers: ' +
                       printRange(limits));
     }