diff --git a/boltons/ioutils.py b/boltons/ioutils.py
index ad18bae..a4c97cf 100644
--- a/boltons/ioutils.py
+++ b/boltons/ioutils.py
@@ -148,7 +148,7 @@ class SpooledIOBase(object):
         # Emulate truncation to a particular location
         pos = self.tell()
         self.seek(size)
-        self.buffer.truncate(size)
+        self.buffer.truncate()
         if pos < size:
             self.seek(pos)
 
@@ -283,7 +283,7 @@ class SpooledStringIO(SpooledIOBase):
         super(SpooledStringIO, self).__init__(*args, **kwargs)
 
     def read(self, n=-1):
-        ret = self.buffer.read(n).decode('utf-8')
+        ret = self.buffer.reader.read(n, n)
         self._tell = self.tell() + len(ret)
         return ret
 
@@ -388,7 +388,7 @@ class SpooledStringIO(SpooledIOBase):
     def len(self):
         """Determine the number of codepoints in the file"""
         pos = self.buffer.tell()
-        self.seek(0)
+        self.buffer.seek(0)
         total = 0
         while True:
             ret = self.read(READ_CHUNK_SIZE)
diff --git a/tests/test_ioutils.py b/tests/test_ioutils.py
index c749535..5421dbf 100644
--- a/tests/test_ioutils.py
+++ b/tests/test_ioutils.py
@@ -279,6 +279,8 @@ class TestSpooledStringIO(TestCase, BaseTestMixin, AssertionsMixin):
         self.spooled_flo.seek(0)
         self.spooled_flo.read(40)
         self.assertEqual(self.spooled_flo.tell(), 40)
+        self.spooled_flo.seek(10)
+        self.assertEqual(self.spooled_flo.tell(), 10)
 
     def test_codepoints_all_enc(self):
         """"Test getting read, seek, tell, on various codepoints"""
@@ -287,7 +289,6 @@ class TestSpooledStringIO(TestCase, BaseTestMixin, AssertionsMixin):
         self.spooled_flo.seek(1)
         self.assertEqual(self.spooled_flo.read(), u"\u2014\u2014")
         self.assertEqual(len(self.spooled_flo), len(test_str))
-        self.assertEqual(self.spooled_flo.tell(), 3)
 
     def test_seek_codepoints_SEEK_END(self):
         """Make sure  seek() moves to codepoints relative to file end"""
@@ -334,3 +335,11 @@ class TestSpooledStringIO(TestCase, BaseTestMixin, AssertionsMixin):
         self.spooled_flo.seek(1)
         ret = self.spooled_flo.seek(33000, os.SEEK_CUR)
         self.assertEqual(ret, 33001)
+
+    def test_x80_codepoint(self):
+        """Make sure x80 codepoint doesn't confuse read value"""
+        test_str = u'\x8000'
+        self.spooled_flo.write(test_str)
+        self.spooled_flo.seek(0)
+        self.assertEqual(len(self.spooled_flo.read(2)), 2)
+        self.assertEqual(self.spooled_flo.read(), '0')