diff --git a/fdroidserver/metadata.py b/fdroidserver/metadata.py
index a4c6bf00..56931fbe 100644
--- a/fdroidserver/metadata.py
+++ b/fdroidserver/metadata.py
@@ -1075,25 +1075,24 @@ def parse_json_metadata(mf, app):
 def parse_yaml_metadata(mf, app):
     yamldata = yaml.load(mf, Loader=YamlLoader)
 
-    for field in yamldata:
-        if field not in yaml_app_fields:
-            warn_or_exception(_('Unrecognised app field: {fieldname}')
-                              .format(fieldname=field))
-    if not yamldata.get('Builds', None):
-        warn_or_exception(_('Missing app field: {fieldname}')
-                          .format(fieldname='Builds'))
-    for build in yamldata.get('Builds', []):
-        # put all build flag keywords into a set to avoid
-        # excessive looping action
-        build_flag_set = set()
-        for build_flag in build.keys():
-            build_flag_set.add(build_flag)
-        for build_flag in build_flag_set:
-            if build_flag not in build_flags:
-                warn_or_exception(_('Unrecognised build flag: {build_flag}')
-                                  .format(build_flag=build_flag))
-
     if yamldata:
+        for field in yamldata:
+            if field not in yaml_app_fields:
+                warn_or_exception(_('Unrecognised app field: {fieldname}')
+                                  .format(fieldname=field))
+        if not yamldata.get('Builds', None):
+            warn_or_exception(_('Missing app field: {fieldname}')
+                              .format(fieldname='Builds'))
+        for build in yamldata.get('Builds', []):
+            # put all build flag keywords into a set to avoid
+            # excessive looping action
+            build_flag_set = set()
+            for build_flag in build.keys():
+                build_flag_set.add(build_flag)
+            for build_flag in build_flag_set:
+                if build_flag not in build_flags:
+                    warn_or_exception(_('Unrecognised build flag: {build_flag}')
+                                      .format(build_flag=build_flag))
         app.update(yamldata)
     return app