diff --git a/lib/compiler/passes/generate-js.js b/lib/compiler/passes/generate-js.js
index 13fd70f..e70d99e 100644
--- a/lib/compiler/passes/generate-js.js
+++ b/lib/compiler/passes/generate-js.js
@@ -1068,8 +1068,7 @@ function generateJS(ast, options) {
       '  function expected(description, location) {',
       '    location = location !== void 0 ? location : peg$computeLocation(peg$savedPos, peg$currPos)',
       '',
-      '    throw peg$buildException(',
-      '      null,',
+      '    throw peg$buildStructuredError(',
       '      [peg$otherExpectation(description)],',
       '      input.substring(peg$savedPos, peg$currPos),',
       '      location',
@@ -1079,7 +1078,7 @@ function generateJS(ast, options) {
       '  function error(message, location) {',
       '    location = location !== void 0 ? location : peg$computeLocation(peg$savedPos, peg$currPos)',
       '',
-      '    throw peg$buildException(message, null, null, location);',
+      '    throw peg$buildSimpleError(message, location);',
       '  }',
       '',
       '  function peg$literalExpectation(text, ignoreCase) {',
@@ -1164,9 +1163,13 @@ function generateJS(ast, options) {
       '    peg$maxFailExpected.push(expected);',
       '  }',
       '',
-      '  function peg$buildException(message, expected, found, location) {',
+      '  function peg$buildSimpleError(message, location) {',
+      '    return new peg$SyntaxError(message, null, null, location);',
+      '  }',
+      '',
+      '  function peg$buildStructuredError(expected, found, location) {',
       '    return new peg$SyntaxError(',
-      '      message !== null ? message : peg$SyntaxError.buildMessage(expected, found),',
+      '      peg$SyntaxError.buildMessage(expected, found),',
       '      expected,',
       '      found,',
       '      location',
@@ -1205,8 +1208,7 @@ function generateJS(ast, options) {
       '      peg$fail(peg$endExpectation());',
       '    }',
       '',
-      '    throw peg$buildException(',
-      '      null,',
+      '    throw peg$buildStructuredError(',
       '      peg$maxFailExpected,',
       '      peg$maxFailPos < input.length ? input.charAt(peg$maxFailPos) : null,',
       '      peg$maxFailPos < input.length',
diff --git a/lib/parser.js b/lib/parser.js
index d6b5f9b..666f2f5 100644
--- a/lib/parser.js
+++ b/lib/parser.js
@@ -523,8 +523,7 @@ function peg$parse(input, options) {
   function expected(description, location) {
     location = location !== void 0 ? location : peg$computeLocation(peg$savedPos, peg$currPos)
 
-    throw peg$buildException(
-      null,
+    throw peg$buildStructuredError(
       [peg$otherExpectation(description)],
       input.substring(peg$savedPos, peg$currPos),
       location
@@ -534,7 +533,7 @@ function peg$parse(input, options) {
   function error(message, location) {
     location = location !== void 0 ? location : peg$computeLocation(peg$savedPos, peg$currPos)
 
-    throw peg$buildException(message, null, null, location);
+    throw peg$buildSimpleError(message, location);
   }
 
   function peg$literalExpectation(text, ignoreCase) {
@@ -619,9 +618,13 @@ function peg$parse(input, options) {
     peg$maxFailExpected.push(expected);
   }
 
-  function peg$buildException(message, expected, found, location) {
+  function peg$buildSimpleError(message, location) {
+    return new peg$SyntaxError(message, null, null, location);
+  }
+
+  function peg$buildStructuredError(expected, found, location) {
     return new peg$SyntaxError(
-      message !== null ? message : peg$SyntaxError.buildMessage(expected, found),
+      peg$SyntaxError.buildMessage(expected, found),
       expected,
       found,
       location
@@ -5021,8 +5024,7 @@ function peg$parse(input, options) {
       peg$fail(peg$endExpectation());
     }
 
-    throw peg$buildException(
-      null,
+    throw peg$buildStructuredError(
       peg$maxFailExpected,
       peg$maxFailPos < input.length ? input.charAt(peg$maxFailPos) : null,
       peg$maxFailPos < input.length