diff --git a/boltons/ioutils.py b/boltons/ioutils.py
index 47f2b6a..22e2444 100644
--- a/boltons/ioutils.py
+++ b/boltons/ioutils.py
@@ -116,7 +116,15 @@ class SpooledIOBase(object):
         return self.buffer.isatty()
 
     def next(self):
-        return self.readline()
+        line = self.readline()
+        if not line:
+            pos = self.buffer.tell()
+            self.buffer.seek(0, os.SEEK_END)
+            if pos == self.buffer.tell():
+                raise StopIteration
+            else:
+                self.buffer.seek(pos)
+        return line
 
     @property
     def closed(self):
@@ -161,11 +169,13 @@ class SpooledIOBase(object):
         self.seek(pos)
         return val
 
+    __next__ = next
+
     def __len__(self):
         return self.len
 
     def __iter__(self):
-        yield self.readline()
+        return self
 
     def __enter__(self):
         return self
@@ -184,7 +194,7 @@ class SpooledIOBase(object):
     def __bool__(self):
         return True
 
-    __nonzero__=__bool__
+    __nonzero__ = __bool__
 
 
 class SpooledBytesIO(SpooledIOBase):
diff --git a/tests/test_ioutils.py b/tests/test_ioutils.py
index a798dcb..98f007e 100644
--- a/tests/test_ioutils.py
+++ b/tests/test_ioutils.py
@@ -142,13 +142,6 @@ class BaseTestMixin(object):
         self.spooled_flo.softspace = True
         self.assertTrue(self.spooled_flo.softspace)
 
-    def test_iter(self):
-        """Make sure iter works as expected"""
-        self.spooled_flo.write(self.test_str)
-        self.spooled_flo.seek(0)
-        self.assertEqual([x for x in self.spooled_flo][0], self.test_str)
-        self.assertEqual([x for x in self.spooled_flo][0], self.data_type())
-
     def test_buf_property(self):
         """'buf' property returns the same value as getvalue()"""
         self.assertEqual(self.spooled_flo.buf, self.spooled_flo.getvalue())
@@ -273,6 +266,12 @@ class TestSpooledBytesIO(TestCase, BaseTestMixin, AssertionsMixin):
         self.assertTrue('content.txt' in doc.namelist())
         doc.close()
 
+    def test_iter(self):
+        """Make sure iter works as expected"""
+        self.spooled_flo.write(b"a\nb")
+        self.spooled_flo.seek(0)
+        self.assertEqual([x for x in self.spooled_flo], [b"a\n", b"b"])
+
 
 class TestSpooledStringIO(TestCase, BaseTestMixin, AssertionsMixin):
     linesep = os.linesep
@@ -405,6 +404,12 @@ class TestSpooledStringIO(TestCase, BaseTestMixin, AssertionsMixin):
         self.spooled_flo.seek(0)
         self.assertEqual(self.spooled_flo.read(3), test_str)
 
+    def test_iter(self):
+        """Make sure iter works as expected"""
+        self.spooled_flo.write(u"a\nb")
+        self.spooled_flo.seek(0)
+        self.assertEqual([x for x in self.spooled_flo], [u"a\n", u"b"])
+
 
 class TestMultiFileReader(TestCase):
     def test_read_seek_bytes(self):