diff --git a/fdroidserver/lint.py b/fdroidserver/lint.py
index bfa380e7..9eaf4b19 100644
--- a/fdroidserver/lint.py
+++ b/fdroidserver/lint.py
@@ -473,6 +473,29 @@ def check_extlib_dir(apps):
         yield _("Unused extlib at %s") % os.path.join(dir_path, path)
 
 
+def check_app_field_types(app):
+    """Check the fields have valid data types"""
+
+    for field in app.keys():
+        v = app.get(field)
+        t = metadata.fieldtype(field)
+        if v is None:
+            continue
+        elif field == 'builds':
+            if not isinstance(v, list):
+                yield(_("{appid}: {field} must be a '{type}', but it is a '{fieldtype}'!")
+                      .format(appid=app.id, field=field,
+                              type='list', fieldtype=v.__class__.__name__))
+        elif t == metadata.TYPE_LIST and not isinstance(v, list):
+            yield(_("{appid}: {field} must be a '{type}', but it is a '{fieldtype}!'")
+                  .format(appid=app.id, field=field,
+                          type='list', fieldtype=v.__class__.__name__))
+        elif t == metadata.TYPE_STRING and not type(v) in (str, bool, dict):
+            yield(_("{appid}: {field} must be a '{type}', but it is a '{fieldtype}'!")
+                  .format(appid=app.id, field=field,
+                          type='str', fieldtype=v.__class__.__name__))
+
+
 def check_for_unsupported_metadata_files(basedir=""):
     """Checks whether any non-metadata files are in metadata/"""
 
@@ -538,6 +561,7 @@ def main():
             continue
 
         app_check_funcs = [
+            check_app_field_types,
             check_regexes,
             check_update_check_data_url,
             check_vercode_operation,
diff --git a/tests/lint.TestCase b/tests/lint.TestCase
index 8255957c..2670c3dd 100755
--- a/tests/lint.TestCase
+++ b/tests/lint.TestCase
@@ -70,6 +70,59 @@ class LintTest(unittest.TestCase):
             logging.debug(warn)
         self.assertTrue(anywarns)
 
+    def test_check_app_field_types(self):
+        config = dict()
+        fdroidserver.common.fill_config_defaults(config)
+        fdroidserver.common.config = config
+        fdroidserver.lint.config = config
+
+        app = fdroidserver.metadata.App()
+        app.id = 'fake.app'
+        app.Name = 'Bad App'
+        app.Summary = 'We pwn you'
+        app.Description = 'These are some back'
+
+        fields = {
+            'AntiFeatures': {
+                'good': [
+                    ['KnownVuln', ],
+                    ['NonFreeNet', 'KnownVuln'],
+                ],
+                'bad': [
+                    'KnownVuln',
+                    'NonFreeNet,KnownVuln',
+                ],
+            },
+            'Categories': {
+                'good': [
+                    ['Sports & Health', ],
+                    ['Multimedia', 'Graphics'],
+                ],
+                'bad': [
+                    'Science & Education',
+                    'Multimedia,Graphics',
+                ],
+            },
+        }
+
+        for field, values in fields.items():
+
+            for bad in values['bad']:
+                anywarns = False
+                app[field] = bad
+                for warn in fdroidserver.lint.check_app_field_types(app):
+                    anywarns = True
+                    logging.debug(warn)
+                self.assertTrue(anywarns)
+
+            for good in values['good']:
+                anywarns = False
+                app[field] = good
+                for warn in fdroidserver.lint.check_app_field_types(app):
+                    anywarns = True
+                    logging.debug(warn)
+                self.assertFalse(anywarns)
+
     def test_check_vercode_operation(self):
         config = dict()
         fdroidserver.common.fill_config_defaults(config)