diff --git a/doc/changelog.txt b/doc/changelog.txt
index 566712fe..807ade8a 100644
--- a/doc/changelog.txt
+++ b/doc/changelog.txt
@@ -3,6 +3,8 @@
 Fixes:
 - checking: Fix broken anchor checking.
   Closes: SF bug #3140765
+- checking: Properly detect filenames with spaces as
+  internal links when given as start URL.
 - logging: Allow Unicode strings to be written to stdout without
   encoding errors.
 - gui: Reset statistics before each run.
diff --git a/linkcheck/checker/fileurl.py b/linkcheck/checker/fileurl.py
index 7c95f5a0..adc7905c 100644
--- a/linkcheck/checker/fileurl.py
+++ b/linkcheck/checker/fileurl.py
@@ -266,14 +266,6 @@ class FileUrl (urlbase.UrlBase):
         @return non-empty regex pattern or None
         @rtype String or None
         """
-        url = absolute_url(self.base_url, self.base_ref, self.parent_url)
-        if not url:
+        if not self.url:
             return None
-        parts = strformat.url_unicode_split(url)
-        path = urlutil.splitparams(parts[2])[0]
-        segments = path.split('/')
-        if not self.is_directory():
-            # cut off filename to have a directory
-            segments = segments[:-1]
-        path = "/".join(segments)
-        return "file://%s" % re.escape(path)
+        return re.escape(self.url)
diff --git a/tests/checker/data/a b/t.txt b/tests/checker/data/a b/t.txt
new file mode 100644
index 00000000..8d1c8b69
--- /dev/null
+++ b/tests/checker/data/a b/t.txt	
@@ -0,0 +1 @@
+ 
diff --git a/tests/checker/test_file.py b/tests/checker/test_file.py
index 9de31bc9..45a45d71 100644
--- a/tests/checker/test_file.py
+++ b/tests/checker/test_file.py
@@ -129,3 +129,19 @@ class TestFile (LinkCheckTest):
             u"valid",
         ]
         self.direct(url, resultlines)
+
+    def test_good_dir_space (self):
+        url = u"file://%(curdir)s/%(datadir)s/a b/" % self.get_attrs()
+        nurl = self.norm(url)
+        resultlines = [
+            u"url %s" % url,
+            u"cache key %s" % nurl,
+            u"real url %s" % nurl,
+            u"valid",
+            u"url t.txt",
+            u"cache key %st.txt" % nurl,
+            u"real url %st.txt" % nurl,
+            u"name t.txt",
+            u"valid",
+        ]
+        self.direct(url, resultlines, recursionlevel=1)