diff --git a/qurator/dinglehopper/cli.py b/qurator/dinglehopper/cli.py
index 31e582b..00221f3 100644
--- a/qurator/dinglehopper/cli.py
+++ b/qurator/dinglehopper/cli.py
@@ -44,13 +44,13 @@ def gen_diff_report(gt_things, ocr_things, css_prefix, joiner, none, align):
 
 def delete_tempcache():
     # Delete all tempfiles and the directory (if empty)
-    tempdir = tempfile.gettempdir() + "/dinglehopper/"
+    tempdir = os.path.join(tempfile.gettempdir(), "dinglehopper/")
     if os.path.exists(tempdir):
         tempfiles = glob.glob(tempdir+"*.np*")
         for tempfilename in tempfiles:
             os.remove(tempfilename)
         if not os.listdir(tempdir):
-            shutil.rmtree(os.path.normpath(tempdir))
+            shutil.rmtree(tempdir)
 
 
 def process(gt, ocr, report_prefix):
diff --git a/qurator/dinglehopper/edit_distance.py b/qurator/dinglehopper/edit_distance.py
index 6f7c286..b224e8f 100644
--- a/qurator/dinglehopper/edit_distance.py
+++ b/qurator/dinglehopper/edit_distance.py
@@ -23,11 +23,12 @@ def levenshtein_matrix(seq1, seq2, tempcache=True):
     strings, e.g. lists of grapheme clusters or lists of word strings.
     """
     if tempcache:
-        hashname = hashlib.sha1(("".join(seq1) + "".join(seq2)).encode("utf-8")).hexdigest()
-        tempdir = os.path.normpath(tempfile.gettempdir() + "/dinglehopper/")
+        hashseq1 = hashlib.sha1(("؟".join(seq1)).encode("utf-8")).hexdigest()
+        hashseq2 = hashlib.sha1(("؟".join(seq2)).encode("utf-8")).hexdigest()
+        tempdir = os.path.join(tempfile.gettempdir(), "dinglehopper/")
         if not os.path.exists(tempdir):
-            os.makedirs(tempdir + "/dinglehopper/")
-        tempfilename = os.path.normpath(tempdir + "/" + hashname + ".npy")
+            os.makedirs(tempdir)
+        tempfilename = os.path.join(tempdir, hashseq1 + "." + hashseq2 + ".npy")
         if os.path.exists(tempfilename):
             return np.load(tempfilename)