diff -r 253c31930b32 Lib/tarfile.py
--- a/Lib/tarfile.py	Sat Jul 26 00:58:55 2014 +0200
+++ b/Lib/tarfile.py	Fri Jul 25 20:02:50 2014 -0400
@@ -1141,7 +1141,7 @@
         # the longname information.
         next.offset = self.offset
         if self.type == GNUTYPE_LONGNAME:
-            next.name = nts(buf, tarfile.encoding, tarfile.errors)
+            next.name = nts(buf, tarfile.encoding, tarfile.errors).rstrip('/')
         elif self.type == GNUTYPE_LONGLINK:
             next.linkname = nts(buf, tarfile.encoding, tarfile.errors)
 
diff -r 253c31930b32 Lib/test/test_tarfile.py
--- a/Lib/test/test_tarfile.py	Sat Jul 26 00:58:55 2014 +0200
+++ b/Lib/test/test_tarfile.py	Fri Jul 25 20:02:50 2014 -0400
@@ -992,6 +992,26 @@
         finally:
             tar.close()
 
+    def test_101_char_dir(self):
+        # Test for bug #21987.
+        name = "x" * 101
+        tar = tarfile.open(tmpname, self.mode)
+        cwd = os.getcwd()
+        try:
+            os.chdir(TEMPDIR)
+            os.mkdir(name)
+            tar.add(name)
+        finally:
+            os.rmdir(name)
+            os.chdir(cwd)
+            tar.close()
+
+        tar = tarfile.open(tmpname)
+        try:
+            tar.getmember(name)
+        finally:
+            tar.close()
+
     def test_tar_size(self):
         # Test for bug #1013882.
         tar = tarfile.open(tmpname, self.mode)