diff --git a/NEWS b/NEWS
index 99be0f9..2b05008 100644
--- a/NEWS
+++ b/NEWS
@@ -35,6 +35,12 @@ with all sufficient information, see the ChangeLog file.
 * lib/drb/drb.rb
  * removed unused argument. https://github.com/ruby/ruby/pull/515
 
+* lib/base64.rb
+ * Base64.urlsafe_encode64: added a "padding" option to suppress
+   the padding character ("=").
+ * Base64.urlsafe_decode64: now it accepts not only correctly-padded
+   input but also unpadded input.
+
 === Built-in global variables compatibility issues
 
 === C API updates
diff --git a/lib/base64.rb b/lib/base64.rb
index 98829f0..45e8516 100644
--- a/lib/base64.rb
+++ b/lib/base64.rb
@@ -77,8 +77,12 @@ module Base64
   # This method complies with ``Base 64 Encoding with URL and Filename Safe
   # Alphabet'' in RFC 4648.
   # The alphabet uses '-' instead of '+' and '_' instead of '/'.
-  def urlsafe_encode64(bin)
-    strict_encode64(bin).tr("+/", "-_")
+  # Note that the result can still contain '='.
+  # You can remove the padding by setting "padding" as false.
+  def urlsafe_encode64(bin, padding: true)
+    str = strict_encode64(bin).tr("+/", "-_")
+    str = str.delete("=") unless padding
+    str
   end
 
   # Returns the Base64-decoded version of +str+.
@@ -86,6 +90,14 @@ module Base64
   # Alphabet'' in RFC 4648.
   # The alphabet uses '-' instead of '+' and '_' instead of '/'.
   def urlsafe_decode64(str)
-    strict_decode64(str.tr("-_", "+/"))
+  #
+  # The padding character is optional.
+  # This method accepts both correctly-padded and unpadded input.
+  # Note that it still rejects incorrectly-padded input.
+    str = str.tr("-_", "+/")
+    if !str.end_with?("=") && str.length % 4 != 0
+      str = str.ljust((str.length + 3) & ~3, "=")
+    end
+    strict_decode64(str)
   end
 end
diff --git a/test/base64/test_base64.rb b/test/base64/test_base64.rb
index c5e61b3..c2cd60a 100644
--- a/test/base64/test_base64.rb
+++ b/test/base64/test_base64.rb
@@ -87,6 +87,13 @@ class TestBase64 < Test::Unit::TestCase
     assert_equal("_-8=", Base64.urlsafe_encode64("\xff\xef"))
   end
 
+  def test_urlsafe_encode64_unpadded
+    assert_equal("", Base64.urlsafe_encode64("", padding: false))
+    assert_equal("AA", Base64.urlsafe_encode64("\0", padding: false))
+    assert_equal("AAA", Base64.urlsafe_encode64("\0\0", padding: false))
+    assert_equal("AAAA", Base64.urlsafe_encode64("\0\0\0", padding: false))
+  end
+
   def test_urlsafe_decode64
     assert_equal("", Base64.urlsafe_decode64(""))
     assert_equal("\0", Base64.urlsafe_decode64("AA=="))
@@ -97,4 +104,11 @@ class TestBase64 < Test::Unit::TestCase
     assert_equal("\377\377\377", Base64.urlsafe_decode64("____"))
     assert_equal("\xff\xef", Base64.urlsafe_decode64("_+8="))
   end
+
+  def test_urlsafe_decode64_unpadded
+    assert_equal("\0", Base64.urlsafe_decode64("AA"))
+    assert_equal("\0\0", Base64.urlsafe_decode64("AAA"))
+    assert_equal("\0\0\0", Base64.urlsafe_decode64("AAAA"))
+    assert_raise(ArgumentError) { Base64.urlsafe_decode64("AA=") }
+  end
 end