diff --git a/Lib/sre_compile.py b/Lib/sre_compile.py
index 7cda2b6..15d2324 100644
--- a/Lib/sre_compile.py
+++ b/Lib/sre_compile.py
@@ -355,8 +355,6 @@ def _optimize_unicode(charset, fixup):
 def _simple(av):
     # check if av is a "simple" operator
     lo, hi = av[2].getwidth()
-    if lo == 0 and hi == MAXREPEAT:
-        raise error, "nothing to repeat"
     return lo == hi == 1 and av[2][0][0] != SUBPATTERN
 
 def _compile_info(code, pattern, flags):
diff --git a/Lib/sre_parse.py b/Lib/sre_parse.py
index 75f8c96..644441d 100644
--- a/Lib/sre_parse.py
+++ b/Lib/sre_parse.py
@@ -147,7 +147,7 @@ class SubPattern:
         REPEATCODES = (MIN_REPEAT, MAX_REPEAT)
         for op, av in self.data:
             if op is BRANCH:
-                i = sys.maxint
+                i = MAXREPEAT - 1
                 j = 0
                 for av in av[1]:
                     l, h = av.getwidth()
@@ -165,14 +165,14 @@ class SubPattern:
                 hi = hi + j
             elif op in REPEATCODES:
                 i, j = av[2].getwidth()
-                lo = lo + long(i) * av[0]
-                hi = hi + long(j) * av[1]
+                lo = lo + i * av[0]
+                hi = hi + j * av[1]
             elif op in UNITCODES:
                 lo = lo + 1
                 hi = hi + 1
             elif op == SUCCESS:
                 break
-        self.width = int(min(lo, sys.maxint)), int(min(hi, sys.maxint))
+        self.width = min(lo, MAXREPEAT - 1), min(hi, MAXREPEAT)
         return self.width
 
 class Tokenizer:
diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py
index 18a81a2..f0827d8 100644
--- a/Lib/test/test_re.py
+++ b/Lib/test/test_re.py
@@ -897,6 +897,17 @@ class ReTests(unittest.TestCase):
         with self.assertRaisesRegexp(sre_constants.error, '\?foo'):
             re.compile('(?P<?foo>)')
 
+    def test_bug_2537(self):
+        # issue 2537: empty submatches
+        for outer_op in ('{0,}', '*', '+', '{1,187}'):
+            for inner_op in ('{0,}', '*', '?'):
+                r = re.compile("^((x|y)%s)%s" % (inner_op, outer_op))
+                m = r.match("xyyzy")
+                self.assertEqual(m.group(0), "xyy")
+                self.assertEqual(m.group(1), "")
+                self.assertEqual(m.group(2), "y")
+
+
 
 def run_re_tests():
     from test.re_tests import tests, SUCCEED, FAIL, SYNTAX_ERROR
diff --git a/Lib/doctest.py b/Lib/doctest.py
index 90bcca1..0ee40a2 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -564,7 +564,7 @@ class DocTestParser:
         # Want consists of any non-blank lines that do not start with PS1.
         (?P<want> (?:(?![ ]*$)    # Not a blank line
                      (?![ ]*>>>)  # Not a line starting with PS1
-                     .*$\n?       # But any other line
+                     .+$\n?       # But any other line
                   )*)
         ''', re.MULTILINE | re.VERBOSE)