diff --git a/CHANGES b/CHANGES
index e3f058095..6485b5037 100644
--- a/CHANGES
+++ b/CHANGES
@@ -59,6 +59,7 @@ Bugs fixed
 * #2521: generated Makefile causes BSD make crashed if sphinx-build not found
 * #2470: ``typing`` backport package causes autodoc errors with python 2.7
 * ``sphinx.ext.intersphinx`` crashes if non-string value is used for key of `intersphinx_mapping`
+* #2518: `intersphinx_mapping` disallows non alphanumeric keys
 
 
 Release 1.4.1 (released Apr 12, 2016)
diff --git a/sphinx/ext/intersphinx.py b/sphinx/ext/intersphinx.py
index 844826e5f..8e6573e8a 100644
--- a/sphinx/ext/intersphinx.py
+++ b/sphinx/ext/intersphinx.py
@@ -274,8 +274,6 @@ def load_mappings(app):
             if not isinstance(name, string_types):
                 app.warn('intersphinx identifier %r is not string. Ignored' % name)
                 continue
-            elif not name.isalnum():
-                app.warn('intersphinx identifier %r is not alphanumeric' % name)
         else:
             # old format, no name
             name, uri, inv = None, key, value
diff --git a/tests/test_ext_intersphinx.py b/tests/test_ext_intersphinx.py
index 099debc1a..13b5d1aff 100644
--- a/tests/test_ext_intersphinx.py
+++ b/tests/test_ext_intersphinx.py
@@ -161,7 +161,7 @@ def test_missing_reference(tempdir, app, status, warning):
 def test_load_mappings_warnings(tempdir, app, status, warning):
     """
     load_mappings issues a warning if new-style mapping
-    identifiers are not alphanumeric
+    identifiers are not string
     """
     inv_file = tempdir / 'inventory'
     inv_file.write_bytes(inventory_v2)
@@ -177,7 +177,7 @@ def test_load_mappings_warnings(tempdir, app, status, warning):
     app.config.intersphinx_cache_limit = 0
     # load the inventory and check if it's done correctly
     load_mappings(app)
-    assert warning.getvalue().count('\n') == 3
+    assert warning.getvalue().count('\n') == 1
 
 
 class TestStripBasicAuth(unittest.TestCase):