diff --git a/qutebrowser/config/configtypes.py b/qutebrowser/config/configtypes.py
index d5696d249..3fd58093c 100644
--- a/qutebrowser/config/configtypes.py
+++ b/qutebrowser/config/configtypes.py
@@ -934,7 +934,6 @@ class QtColor(BaseType):
         if val.endswith('%'):
             val = val[:-1]
             mult = 255.0 / 100
-            return int(float(val) * 255.0 / 100.0)
 
         try:
             return int(float(val) * mult)
@@ -948,19 +947,21 @@ class QtColor(BaseType):
         elif not value:
             return None
 
-        if value.endswith(')'):
+        if '(' in value and value.endswith(')'):
             openparen = value.index('(')
             kind = value[:openparen]
             vals = value[openparen+1:-1].split(',')
             vals = [self._parse_value(v) for v in vals]
             if kind == 'rgba' and len(vals) == 4:
                 return QColor.fromRgb(*vals)
-            if kind == 'rgb' and len(vals) == 3:
+            elif kind == 'rgb' and len(vals) == 3:
                 return QColor.fromRgb(*vals)
-            if kind == 'hsva' and len(vals) == 4:
+            elif kind == 'hsva' and len(vals) == 4:
                 return QColor.fromHsv(*vals)
-            if kind == 'hsv' and len(vals) == 3:
+            elif kind == 'hsv' and len(vals) == 3:
                 return QColor.fromHsv(*vals)
+            else:
+                raise configexc.ValidationError(value, "must be a valid color")
 
         color = QColor(value)
         if color.isValid():
diff --git a/tests/unit/config/test_configtypes.py b/tests/unit/config/test_configtypes.py
index 9e67cc725..afbd7dfeb 100644
--- a/tests/unit/config/test_configtypes.py
+++ b/tests/unit/config/test_configtypes.py
@@ -21,7 +21,6 @@
 import re
 import json
 import math
-import itertools
 import warnings
 import inspect
 import functools
@@ -1247,11 +1246,9 @@ class TestQtColor:
         # however this is consistent with Qt's CSS parser
         # https://bugreports.qt.io/browse/QTBUG-70897
         ('hsv(10%,10%,10%)', QColor.fromHsv(25, 25, 25)),
+        ('hsva(10%,20%,30%,40%)', QColor.fromHsv(25, 51, 76, 102)),
     ])
     def test_valid(self, val, expected):
-        act = configtypes.QtColor().to_py(val)
-        print(expected.hue(), expected.saturation(), expected.value(), expected.alpha())
-        print(act.hue(), act.saturation(), act.value(), act.alpha())
         assert configtypes.QtColor().to_py(val) == expected
 
     @pytest.mark.parametrize('val', [
@@ -1262,6 +1259,13 @@ class TestQtColor:
         '42',
         'foo(1, 2, 3)',
         'rgb(1, 2, 3',
+        'rgb)',
+        'rgb(1, 2, 3))',
+        'rgb((1, 2, 3)',
+        'rgb()',
+        'rgb(1, 2, 3, 4)',
+        'rgba(1, 2, 3)',
+        'rgb(10%%, 0, 0)',
     ])
     def test_invalid(self, val):
         with pytest.raises(configexc.ValidationError):