diff --git a/qutebrowser/browser/navigate.py b/qutebrowser/browser/navigate.py
index bffbf6fb8..194246344 100644
--- a/qutebrowser/browser/navigate.py
+++ b/qutebrowser/browser/navigate.py
@@ -132,6 +132,7 @@ def path_up(url, count):
         url: The current url.
         count: The number of levels to go up in the url.
     """
+    urlutils.ensure_valid(url)
     url = url.adjusted(QUrl.RemoveFragment | QUrl.RemoveQuery)
     path = url.path()
     if not path or path == '/':
@@ -147,6 +148,7 @@ def strip(url, count):
     """Strip fragment/query from a URL."""
     if count != 1:
         raise Error("Count is not supported when stripping URL components")
+    urlutils.ensure_valid(url)
     return url.adjusted(QUrl.RemoveFragment | QUrl.RemoveQuery)
 
 
diff --git a/tests/unit/browser/test_navigate.py b/tests/unit/browser/test_navigate.py
index 40f7a4673..5fe0acbf6 100644
--- a/tests/unit/browser/test_navigate.py
+++ b/tests/unit/browser/test_navigate.py
@@ -172,7 +172,7 @@ class TestIncDec:
 
     def test_invalid_url(self):
         with pytest.raises(urlutils.InvalidUrlError):
-            navigate.incdec(QUrl(""), 1, "increment")
+            navigate.incdec(QUrl(), 1, "increment")
 
     def test_wrong_mode(self):
         """Test if incdec rejects a wrong parameter for inc_or_dec."""
@@ -196,6 +196,10 @@ class TestUp:
         new = navigate.path_up(url, count)
         assert new == QUrl(url_base + expected_suffix)
 
+    def test_invalid_url(self):
+        with pytest.raises(urlutils.InvalidUrlError):
+            navigate.path_up(QUrl(), count=1)
+
 
 class TestStrip:
 
@@ -216,3 +220,7 @@ class TestStrip:
     def test_count(self):
         with pytest.raises(navigate.Error, match='Count is not supported'):
             navigate.strip(QUrl('https://example.com/'), count=2)
+
+    def test_invalid_url(self):
+        with pytest.raises(urlutils.InvalidUrlError):
+            navigate.strip(QUrl(), count=1)