diff --git a/json5/json5.g b/json5/json5.g
index 1bbb798..a33ccd2 100644
--- a/json5/json5.g
+++ b/json5/json5.g
@@ -4,7 +4,7 @@ sp             = ws*
 
 ws             = '\u0020' | eol | comment
                | '\u0009' | '\u000B' | '\u000C' | '\u00A0' | '\uFEFF'
-               | anything:x ?( is_unicat(x, 'Zs') ) -> x
+               | ~~(anything:x ?( is_unicat(x, 'Zs') )) anything:x -> x
 
 eol            = '\u000D' '\u000A' | '\u000D' | '\u000A'
                | '\u2028' | '\u2029'
diff --git a/json5/parser.py b/json5/parser.py
index a2a0039..86bc194 100644
--- a/json5/parser.py
+++ b/json5/parser.py
@@ -70,11 +70,13 @@ def _bind(self, rule, var):
 
     def _not(self, rule):
         p = self.pos
+        errpos = self.errpos
         rule()
         if self.failed:
             self._succeed(None, p)
         else:
             self._rewind(p)
+            self.errpos = errpos
             self._fail()
 
     def _opt(self, rule):
@@ -100,8 +102,6 @@ def _star(self, rule, vs=None):
             rule()
             if self.failed:
                 self._rewind(p)
-                if p < self.errpos:
-                    self.errpos = p
                 break
             else:
                 vs.append(self.val)
@@ -200,11 +200,21 @@ def _ws__c7_(self):
 
     def _ws__c8_(self):
         self._push('ws__c8')
-        self._seq([lambda: self._bind(self._anything_, 'x'), self._ws__c8__s1_,
+        self._seq([self._ws__c8__s0_, lambda: self._bind(self._anything_, 'x'),
                    lambda: self._succeed(self._get('x'))])
         self._pop('ws__c8')
 
-    def _ws__c8__s1_(self):
+    def _ws__c8__s0_(self):
+        self._not(lambda: self._not(self._ws__c8__s0_n_n_))
+
+    def _ws__c8__s0_n_n_(self):
+        (lambda: self._choose([self._ws__c8__s0_n_n_g__c0_]))()
+
+    def _ws__c8__s0_n_n_g__c0_(self):
+        self._seq([lambda: self._bind(self._anything_, 'x'),
+                   self._ws__c8__s0_n_n_g__c0__s1_])
+
+    def _ws__c8__s0_n_n_g__c0__s1_(self):
         v = self._is_unicat(self._get('x'), 'Zs')
         if v:
             self._succeed(v)
diff --git a/tests/lib_test.py b/tests/lib_test.py
index f978650..a6d2473 100644
--- a/tests/lib_test.py
+++ b/tests/lib_test.py
@@ -252,6 +252,21 @@ def test_whitespace(self):
         self.check(u'\u2028 1', 1)
         self.check(u'\u2029 1', 1)
 
+    def test_error_reporting(self):
+        self.check_fail('[ ,]',
+            err='<string>:1 Unexpected "," at column 3')
+
+        self.check_fail(
+            '{\n'
+            '    version: "1.0",\n'
+            '    author: "John Smith",\n'
+            '    people : [\n'
+            '        "Monty",\n'
+            '        "Python"foo\n'
+            '    ]\n'
+            '}\n',
+            err='<string>:6 Unexpected "f" at column 17')
+
 
 class TestDump(unittest.TestCase):
     def test_basic(self):