diff --git a/fdroidserver/metadata.py b/fdroidserver/metadata.py
index 5531d369..b1be88f8 100644
--- a/fdroidserver/metadata.py
+++ b/fdroidserver/metadata.py
@@ -1159,10 +1159,19 @@ def post_parse_yaml_metadata(yamldata):
         for flag in build.keys():
             _flagtype = flagtype(flag)
 
-            # concatenate script flags into a single string if they are stored as list
             if _flagtype is TYPE_SCRIPT:
+                # concatenate script flags into a single string if they are stored as list
                 if isinstance(build[flag], list):
                     build[flag] = ' && '.join(build[flag])
+            elif _flagtype is TYPE_STRING:
+                # things like versionNames are strings, but without quotes can be numbers
+                if isinstance(build[flag], float) or isinstance(build[flag], int):
+                    build[flag] = str(build[flag])
+            elif _flagtype is TYPE_INT:
+                # versionCode must be int
+                if not isinstance(build[flag], int):
+                    warn_or_exception(_('{build_flag} must be an integer, found: {value}')
+                                      .format(build_flag=flag, value=build[flag]))
 
 
 def write_yaml(mf, app):
diff --git a/tests/metadata.TestCase b/tests/metadata.TestCase
index c2c9aa57..ff0e11d7 100755
--- a/tests/metadata.TestCase
+++ b/tests/metadata.TestCase
@@ -15,6 +15,7 @@ import unittest
 import yaml
 import tempfile
 import textwrap
+from collections import OrderedDict
 from unittest import mock
 
 localmodule = os.path.realpath(
@@ -180,6 +181,50 @@ class MetadataTest(unittest.TestCase):
                 self.maxDiff = None
                 self.assertEqual(result.read(), orig.read())
 
+    def test_post_parse_yaml_metadata(self):
+        fdroidserver.metadata.warnings_action = 'error'
+        yamldata = OrderedDict()
+        builds = []
+        yamldata['Builds'] = builds
+        build = OrderedDict()
+        builds.append(build)
+
+        build['versionCode'] = 1.1
+        self.assertRaises(fdroidserver.exception.MetaDataException,
+                          fdroidserver.metadata.post_parse_yaml_metadata, yamldata)
+
+        build['versionCode'] = '1'
+        self.assertRaises(fdroidserver.exception.MetaDataException,
+                          fdroidserver.metadata.post_parse_yaml_metadata, yamldata)
+
+        build['versionCode'] = 1
+        build['versionName'] = 1
+        fdroidserver.metadata.post_parse_yaml_metadata(yamldata)
+        self.assertNotEqual(1, yamldata['Builds'][0]['versionName'])
+        self.assertEqual('1', yamldata['Builds'][0]['versionName'])
+        self.assertEqual(1, yamldata['Builds'][0]['versionCode'])
+
+        build['versionName'] = 1.0
+        fdroidserver.metadata.post_parse_yaml_metadata(yamldata)
+        self.assertNotEqual(1.0, yamldata['Builds'][0]['versionName'])
+        self.assertEqual('1.0', yamldata['Builds'][0]['versionName'])
+
+        build['commit'] = 1.0
+        fdroidserver.metadata.post_parse_yaml_metadata(yamldata)
+        self.assertNotEqual(1.0, yamldata['Builds'][0]['commit'])
+        self.assertEqual('1.0', yamldata['Builds'][0]['commit'])
+
+        teststr = '98234fab134b'
+        build['commit'] = teststr
+        fdroidserver.metadata.post_parse_yaml_metadata(yamldata)
+        self.assertEqual(teststr, yamldata['Builds'][0]['commit'])
+
+        testcommitid = 1234567890
+        build['commit'] = testcommitid
+        fdroidserver.metadata.post_parse_yaml_metadata(yamldata)
+        self.assertNotEqual(testcommitid, yamldata['Builds'][0]['commit'])
+        self.assertEqual('1234567890', yamldata['Builds'][0]['commit'])
+
     def test_read_metadata_sort_by_time(self):
         testdir = tempfile.mkdtemp(prefix=inspect.currentframe().f_code.co_name, dir=self.tmpdir)
         metadatadir = os.path.join(testdir, 'metadata')