diff --git a/qutebrowser/config/configfiles.py b/qutebrowser/config/configfiles.py
index 8b16c701a..11e059302 100644
--- a/qutebrowser/config/configfiles.py
+++ b/qutebrowser/config/configfiles.py
@@ -201,17 +201,37 @@ class YamlConfig(QObject):
 
     def _build_values(self, settings):
         """Build up self._values from the values in the given dict."""
+        errors = []
         for name, yaml_values in settings.items():
+            if not isinstance(yaml_values, dict):
+                errors.append(configexc.ConfigErrorDesc(
+                    "While parsing {!r}".format(name), "value is not a dict"))
+                continue
+
             values = configutils.Values(configdata.DATA[name])
             if 'global' in yaml_values:
                 values.add(yaml_values.pop('global'))
 
-            # FIXME:conf what if yaml_values is not a dict...
             for pattern, value in yaml_values.items():
-                values.add(value, pattern)
+                if not isinstance(pattern, str):
+                    errors.append(configexc.ConfigErrorDesc(
+                        "While parsing {!r}".format(name),
+                        "pattern is not of type string"))
+                    continue
+                try:
+                    urlpattern = urlmatch.UrlPattern(pattern)
+                except urlmatch.ParseError as e:
+                    errors.append(configexc.ConfigErrorDesc(
+                        "While parsing pattern {!r} for {!r}"
+                        .format(pattern, name), e))
+                    continue
+                values.add(value, urlpattern)
 
             self._values[name] = values
 
+        if errors:
+            raise configexc.ConfigFileErrors('autoconfig.yml', errors)
+
     def _handle_migrations(self, settings):
         """Migrate older configs to the newest format."""
         # Simple renamed/deleted options
diff --git a/tests/unit/config/test_configfiles.py b/tests/unit/config/test_configfiles.py
index 0e173e8ff..728dbb794 100644
--- a/tests/unit/config/test_configfiles.py
+++ b/tests/unit/config/test_configfiles.py
@@ -297,6 +297,12 @@ class TestYaml:
         ('settings: {}', 'While loading data',
          "Toplevel object does not contain 'config_version' key"),
         ('42', 'While loading data', "Toplevel object is not a dict"),
+        ('settings: {"content.images": 42}\nconfig_version: 2',
+         "While parsing 'content.images'", "value is not a dict"),
+        ('settings: {"content.images": {"https://": true}}\nconfig_version: 2',
+         "While parsing pattern 'https://' for 'content.images'", "Pattern without host"),
+        ('settings: {"content.images": {true: true}}\nconfig_version: 2',
+         "While parsing 'content.images'", "pattern is not of type string"),
     ])
     def test_invalid(self, yaml, autoconfig, line, text, exception):
         autoconfig.write_raw(line)