diff --git a/src/core/cmap.js b/src/core/cmap.js
index 3f992bfb7..1c0e0b15e 100644
--- a/src/core/cmap.js
+++ b/src/core/cmap.js
@@ -14,7 +14,8 @@
  */
 
 import {
-  CMapCompressionType, FormatError, isString, MissingDataException, Util, warn
+  CMapCompressionType, FormatError, isString, MissingDataException,
+  unreachable, Util, warn
 } from '../shared/util';
 import { isCmd, isEOF, isName, isStream } from './primitives';
 import { Lexer } from './parser';
@@ -353,19 +354,19 @@ var IdentityCMap = (function IdentityCMapClosure() {
     addCodespaceRange: CMap.prototype.addCodespaceRange,
 
     mapCidRange(low, high, dstLow) {
-      throw new Error('should not call mapCidRange');
+      unreachable('should not call mapCidRange');
     },
 
     mapBfRange(low, high, dstLow) {
-      throw new Error('should not call mapBfRange');
+      unreachable('should not call mapBfRange');
     },
 
     mapBfRangeToArray(low, high, array) {
-      throw new Error('should not call mapBfRangeToArray');
+      unreachable('should not call mapBfRangeToArray');
     },
 
     mapOne(src, dst) {
-      throw new Error('should not call mapCidOne');
+      unreachable('should not call mapCidOne');
     },
 
     lookup(code) {
@@ -402,7 +403,7 @@ var IdentityCMap = (function IdentityCMapClosure() {
     },
 
     get isIdentityCMap() {
-      throw new Error('should not access .isIdentityCMap');
+      unreachable('should not access .isIdentityCMap');
     },
   };
 
diff --git a/src/core/colorspace.js b/src/core/colorspace.js
index ca173b913..f92aaba5d 100644
--- a/src/core/colorspace.js
+++ b/src/core/colorspace.js
@@ -13,7 +13,9 @@
  * limitations under the License.
  */
 
-import { FormatError, info, isString, shadow, warn } from '../shared/util';
+import {
+  FormatError, info, isString, shadow, unreachable, warn
+} from '../shared/util';
 import { isDict, isName, isStream } from './primitives';
 
 var ColorSpace = (function ColorSpaceClosure() {
@@ -54,7 +56,7 @@ var ColorSpace = (function ColorSpaceClosure() {
 
   // Constructor should define this.numComps, this.defaultColor, this.name
   function ColorSpace() {
-    throw new Error('should not call ColorSpace constructor');
+    unreachable('should not call ColorSpace constructor');
   }
 
   ColorSpace.prototype = {
@@ -74,7 +76,7 @@ var ColorSpace = (function ColorSpaceClosure() {
      */
     getRgbItem: function ColorSpace_getRgbItem(src, srcOffset,
                                                dest, destOffset) {
-      throw new Error('Should not call ColorSpace.getRgbItem');
+      unreachable('Should not call ColorSpace.getRgbItem');
     },
     /**
      * Converts the specified number of the color values to the RGB colors.
@@ -88,7 +90,7 @@ var ColorSpace = (function ColorSpaceClosure() {
     getRgbBuffer: function ColorSpace_getRgbBuffer(src, srcOffset, count,
                                                    dest, destOffset, bits,
                                                    alpha01) {
-      throw new Error('Should not call ColorSpace.getRgbBuffer');
+      unreachable('Should not call ColorSpace.getRgbBuffer');
     },
     /**
      * Determines the number of bytes required to store the result of the
@@ -97,7 +99,7 @@ var ColorSpace = (function ColorSpaceClosure() {
      */
     getOutputLength: function ColorSpace_getOutputLength(inputLength,
                                                          alpha01) {
-      throw new Error('Should not call ColorSpace.getOutputLength');
+      unreachable('Should not call ColorSpace.getOutputLength');
     },
     /**
      * Returns true if source data will be equal the result/output data.
diff --git a/src/core/font_renderer.js b/src/core/font_renderer.js
index 2673a61ba..15d12b836 100644
--- a/src/core/font_renderer.js
+++ b/src/core/font_renderer.js
@@ -13,7 +13,9 @@
  * limitations under the License.
  */
 
-import { bytesToString, FormatError, Util } from '../shared/util';
+import {
+   bytesToString, FormatError, unreachable, Util
+} from '../shared/util';
 import { CFFParser } from './cff_parser';
 import { getGlyphsUnicode } from './glyphlist';
 import { StandardEncoding } from './encodings';
@@ -628,7 +630,7 @@ var FontRendererFactory = (function FontRendererFactoryClosure() {
     },
 
     compileGlyphImpl() {
-      throw new Error('Children classes should implement this.');
+      unreachable('Children classes should implement this.');
     },
 
     hasBuiltPath(unicode) {
diff --git a/src/core/fonts.js b/src/core/fonts.js
index 97f387bcf..ac1938486 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -15,7 +15,7 @@
 
 import {
   bytesToString, FONT_IDENTITY_MATRIX, FontType, FormatError, info, isNum,
-  isSpace, MissingDataException, readUint32, shadow, string32, warn
+  isSpace, MissingDataException, readUint32, shadow, string32, unreachable, warn
 } from '../shared/util';
 import {
   CFF, CFFCharset, CFFCompiler, CFFHeader, CFFIndex, CFFParser, CFFPrivateDict,
@@ -295,7 +295,7 @@ var IdentityToUnicodeMap = (function IdentityToUnicodeMapClosure() {
     },
 
     amend(map) {
-      throw new Error('Should not call amend()');
+      unreachable('Should not call amend()');
     },
   };
 
diff --git a/src/core/function.js b/src/core/function.js
index 5ad151206..00c4f1b07 100644
--- a/src/core/function.js
+++ b/src/core/function.js
@@ -14,7 +14,7 @@
  */
 
 import {
-  FormatError, info, isBool, isEvalSupported, shadow
+  FormatError, info, isBool, isEvalSupported, shadow, unreachable
 } from '../shared/util';
 import { isDict, isStream } from './primitives';
 import { PostScriptLexer, PostScriptParser } from './ps_parser';
@@ -822,7 +822,7 @@ var PostScriptCompiler = (function PostScriptCompilerClosure() {
     this.type = type;
   }
   AstNode.prototype.visit = function (visitor) {
-    throw new Error('abstract method');
+    unreachable('abstract method');
   };
 
   function AstArgument(index, min, max) {
diff --git a/src/core/obj.js b/src/core/obj.js
index 622602991..6af60f1f3 100644
--- a/src/core/obj.js
+++ b/src/core/obj.js
@@ -16,7 +16,8 @@
 import {
   bytesToString, createPromiseCapability, createValidAbsoluteUrl, FormatError,
   info, InvalidPDFException, isBool, isString, MissingDataException, shadow,
-  stringToPDFString, stringToUTF8String, Util, warn, XRefParseException
+  stringToPDFString, stringToUTF8String, unreachable, Util, warn,
+  XRefParseException
 } from '../shared/util';
 import {
   Dict, isCmd, isDict, isName, isRef, isRefsEqual, isStream, Ref, RefSet,
@@ -1474,7 +1475,7 @@ var XRef = (function XRefClosure() {
  */
 var NameOrNumberTree = (function NameOrNumberTreeClosure() {
   function NameOrNumberTree(root, xref) {
-    throw new Error('Cannot initialize NameOrNumberTree.');
+    unreachable('Cannot initialize NameOrNumberTree.');
   }
 
   NameOrNumberTree.prototype = {
diff --git a/src/core/pattern.js b/src/core/pattern.js
index a8df287b7..236c58fc4 100644
--- a/src/core/pattern.js
+++ b/src/core/pattern.js
@@ -34,14 +34,14 @@ var ShadingType = {
 var Pattern = (function PatternClosure() {
   // Constructor should define this.getPattern
   function Pattern() {
-    throw new Error('should not call Pattern constructor');
+    unreachable('should not call Pattern constructor');
   }
 
   Pattern.prototype = {
     // Input: current Canvas context
     // Output: the appropriate fillStyle or strokeStyle
     getPattern: function Pattern_getPattern(ctx) {
-      throw new Error(`Should not call Pattern.getStyle: ${ctx}`);
+      unreachable(`Should not call Pattern.getStyle: ${ctx}`);
     },
   };
 
diff --git a/src/core/pdf_manager.js b/src/core/pdf_manager.js
index 8cf881616..9ed6be87f 100644
--- a/src/core/pdf_manager.js
+++ b/src/core/pdf_manager.js
@@ -15,7 +15,7 @@
 
 import {
   createPromiseCapability, createValidAbsoluteUrl, MissingDataException,
-  NotImplementedException, shadow, Util, warn
+  NotImplementedException, shadow, unreachable, Util, warn
 } from '../shared/util';
 import { ChunkedStreamManager } from './chunked_stream';
 import { PDFDocument } from './document';
@@ -23,7 +23,7 @@ import { Stream } from './stream';
 
 var BasePdfManager = (function BasePdfManagerClosure() {
   function BasePdfManager() {
-    throw new Error('Cannot initialize BaseManagerManager');
+    unreachable('Cannot initialize BaseManagerManager');
   }
 
   BasePdfManager.prototype = {
diff --git a/src/display/annotation_layer.js b/src/display/annotation_layer.js
index 073c9cfa5..8c3212fa4 100644
--- a/src/display/annotation_layer.js
+++ b/src/display/annotation_layer.js
@@ -18,7 +18,8 @@ import {
   getFilenameFromUrl, LinkTarget
 } from './dom_utils';
 import {
-  AnnotationBorderStyleType, AnnotationType, stringToPDFString, Util, warn
+  AnnotationBorderStyleType, AnnotationType, stringToPDFString, unreachable,
+  Util, warn
 } from '../shared/util';
 
 /**
@@ -261,7 +262,7 @@ class AnnotationElement {
    * @memberof AnnotationElement
    */
   render() {
-    throw new Error('Abstract method `AnnotationElement.render` called');
+    unreachable('Abstract method `AnnotationElement.render` called');
   }
 }
 
diff --git a/src/display/api.js b/src/display/api.js
index a3fa08ce1..785745015 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -18,7 +18,8 @@ import {
   assert, createPromiseCapability, getVerbosityLevel, info, InvalidPDFException,
   isArrayBuffer, isSameOrigin, loadJpegStream, MessageHandler,
   MissingPDFException, NativeImageDecoding, PageViewport, PasswordException,
-  stringToBytes, UnexpectedResponseException, UnknownErrorException, Util, warn
+  stringToBytes, UnexpectedResponseException, UnknownErrorException,
+  unreachable, Util, warn
 } from '../shared/util';
 import {
   DOMCanvasFactory, DOMCMapReaderFactory, DummyStatTimer, getDefaultSetting,
@@ -475,7 +476,7 @@ var PDFDataRangeTransport = (function pdfDataRangeTransportClosure() {
 
     requestDataRange:
         function PDFDataRangeTransport_requestDataRange(begin, end) {
-      throw new Error('Abstract method PDFDataRangeTransport.requestDataRange');
+      unreachable('Abstract method PDFDataRangeTransport.requestDataRange');
     },
 
     abort: function PDFDataRangeTransport_abort() {
diff --git a/src/display/canvas.js b/src/display/canvas.js
index 6467f23d1..108c961f4 100644
--- a/src/display/canvas.js
+++ b/src/display/canvas.js
@@ -15,7 +15,7 @@
 
 import {
   FONT_IDENTITY_MATRIX, IDENTITY_MATRIX, ImageKind, info, isLittleEndian, isNum,
-  OPS, shadow, TextRenderingMode, Util, warn
+  OPS, shadow, TextRenderingMode, unreachable, Util, warn
 } from '../shared/util';
 import { getShadingPatternFromIR, TilingPattern } from './pattern_helper';
 
@@ -1733,10 +1733,10 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
 
     // Images
     beginInlineImage: function CanvasGraphics_beginInlineImage() {
-      throw new Error('Should not call beginInlineImage');
+      unreachable('Should not call beginInlineImage');
     },
     beginImageData: function CanvasGraphics_beginImageData() {
-      throw new Error('Should not call beginImageData');
+      unreachable('Should not call beginImageData');
     },
 
     paintFormXObjectBegin: function CanvasGraphics_paintFormXObjectBegin(matrix,
diff --git a/src/display/dom_utils.js b/src/display/dom_utils.js
index 45ab29c06..894addde7 100644
--- a/src/display/dom_utils.js
+++ b/src/display/dom_utils.js
@@ -14,7 +14,8 @@
  */
 
 import {
-  assert, CMapCompressionType, removeNullCharacters, stringToBytes, warn
+  assert, CMapCompressionType, removeNullCharacters, stringToBytes,
+  unreachable, warn
 } from '../shared/util';
 import globalScope from '../shared/global_scope';
 
@@ -527,7 +528,7 @@ class StatTimer {
  */
 class DummyStatTimer {
   constructor() {
-    throw new Error('Cannot initialize DummyStatTimer.');
+    unreachable('Cannot initialize DummyStatTimer.');
   }
 
   static reset() {}