diff --git a/distlib/util.py b/distlib/util.py
index aa76a97..0d5bd7a 100644
--- a/distlib/util.py
+++ b/distlib/util.py
@@ -789,7 +789,7 @@ def get_cache_base(suffix=None):
     return os.path.join(result, suffix)
 
 
-def path_to_cache_dir(path):
+def path_to_cache_dir(path, use_abspath=True):
     """
     Convert an absolute path to a directory name for use in a cache.
 
@@ -799,7 +799,7 @@ def path_to_cache_dir(path):
     #. Any occurrence of ``os.sep`` is replaced with ``'--'``.
     #. ``'.cache'`` is appended.
     """
-    d, p = os.path.splitdrive(os.path.abspath(path))
+    d, p = os.path.splitdrive(os.path.abspath(path) if use_abspath else path)
     if d:
         d = d.replace(':', '---')
     p = p.replace(os.sep, '--')
@@ -981,11 +981,11 @@ def __init__(self, base):
             logger.warning('Directory \'%s\' is not private', base)
         self.base = os.path.abspath(os.path.normpath(base))
 
-    def prefix_to_dir(self, prefix):
+    def prefix_to_dir(self, prefix, use_abspath=True):
         """
         Converts a resource prefix to a directory name in the cache.
         """
-        return path_to_cache_dir(prefix)
+        return path_to_cache_dir(prefix, use_abspath=use_abspath)
 
     def clear(self):
         """
diff --git a/distlib/wheel.py b/distlib/wheel.py
index 0034276..e04a515 100644
--- a/distlib/wheel.py
+++ b/distlib/wheel.py
@@ -752,7 +752,7 @@ def _get_extensions(self):
                     wf = wrapper(bf)
                     extensions = json.load(wf)
                     cache = self._get_dylib_cache()
-                    prefix = cache.prefix_to_dir(pathname)
+                    prefix = cache.prefix_to_dir(self.filename, use_abspath=False)
                     cache_base = os.path.join(cache.base, prefix)
                     if not os.path.isdir(cache_base):
                         os.makedirs(cache_base)
diff --git a/tests/test_util.py b/tests/test_util.py
index 936e05e..ee28574 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -99,6 +99,11 @@ def test_cache_base(self):
     @unittest.skipIf(os.name != 'posix', 'Test is only valid for POSIX')
     def test_path_to_cache_dir_posix(self):
         self.assertEqual(path_to_cache_dir('/home/user/some-file.zip'), '--home--user--some-file.zip.cache')
+        self.assertEqual(path_to_cache_dir('path/to/some-file.zip'),
+                         os.path.splitext(path_to_cache_dir(os.path.dirname(HERE)))[0] +
+                         '--path--to--some-file.zip.cache')
+        self.assertEqual(path_to_cache_dir('path/to/some-file.zip', use_abspath=False),
+                         'path--to--some-file.zip.cache')
 
     @unittest.skipIf(os.name != 'nt', 'Test is only valid for Windows')
     def test_path_to_cache_dir_nt(self):