diff --git a/semver.py b/semver.py
index d234f26a..ec764946 100644
--- a/semver.py
+++ b/semver.py
@@ -99,11 +99,11 @@ class VersionInfo(object):
     __slots__ = ('_major', '_minor', '_patch', '_prerelease', '_build')
 
     def __init__(self, major, minor=0, patch=0, prerelease=None, build=None):
-        self._major = major
-        self._minor = minor
-        self._patch = patch
-        self._prerelease = prerelease
-        self._build = build
+        self._major = int(major)
+        self._minor = int(minor)
+        self._patch = int(patch)
+        self._prerelease = None if prerelease is None else str(prerelease)
+        self._build = None if build is None else str(build)
 
     @property
     def major(self):
diff --git a/test_semver.py b/test_semver.py
index 96b78967..a9b1061e 100644
--- a/test_semver.py
+++ b/test_semver.py
@@ -497,3 +497,37 @@ def test_immutable_unknown_attribute(version):
 def test_version_info_should_be_iterable(version):
     assert tuple(version) == (version.major, version.minor, version.patch,
                               version.prerelease, version.build)
+
+
+def test_should_compare_prerelease_and_build_with_numbers():
+    assert VersionInfo(major=1, minor=9, patch=1, prerelease=1, build=1) < \
+           VersionInfo(major=1, minor=9, patch=1, prerelease=2, build=1)
+    assert VersionInfo(1, 9, 1, 1, 1) < VersionInfo(1, 9, 1, 2, 1)
+    assert VersionInfo('2') < VersionInfo(10)
+    assert VersionInfo('2') < VersionInfo('10')
+
+
+def test_should_be_able_to_use_strings_as_major_minor_patch():
+    v = VersionInfo('1', '2', '3')
+    assert isinstance(v.major, int)
+    assert isinstance(v.minor, int)
+    assert isinstance(v.patch, int)
+    assert v.prerelease is None
+    assert v.build is None
+    assert VersionInfo('1', '2', '3') == VersionInfo(1, 2, 3)
+
+
+def test_using_non_numeric_string_as_major_minor_patch_throws():
+    with pytest.raises(ValueError):
+        VersionInfo('a')
+    with pytest.raises(ValueError):
+        VersionInfo(1, 'a')
+    with pytest.raises(ValueError):
+        VersionInfo(1, 2, 'a')
+
+
+def test_should_be_able_to_use_integers_as_prerelease_build():
+    v = VersionInfo(1, 2, 3, 4, 5)
+    assert isinstance(v.prerelease, str)
+    assert isinstance(v.build, str)
+    assert VersionInfo(1, 2, 3, 4, 5) == VersionInfo(1, 2, 3, '4', '5')