diff --git a/.travis.yml b/.travis.yml
index 0e7c860..42ca363 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,10 @@
 language: ruby
 rvm:
-  - 2.4.2
-  - 2.3.5
-  - 2.2.8
-  - 2.1
+  - 2.5.1
+  - 2.4.4
+  - 2.3.7
+  - 2.2.10
+  - 2.1.10
   - 2.0.0
   - 1.9.3
   - jruby-9.1.9.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c7887ca..e185e7e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 0.9.0 (2018-08-16)
+* Add RemoteServerError class for 5xx level errors.
+* Allow to_json to be called with arguments
+* Expires_in now sets and reflects current expires_at value
+* Expires_within(0) now returns false when expires_at is nil.
+
 ## 0.8.1 (2017-10-13)
 
 * Restore support for Ruby 1.9.3
diff --git a/README.md b/README.md
index 217b9e5..43ea177 100644
--- a/README.md
+++ b/README.md
@@ -7,8 +7,8 @@
   <dt>License</dt><dd>Apache 2.0</dd>
 </dl>
 
+[![Gem Version](https://badge.fury.io/rb/signet.svg)](https://badge.fury.io/rb/signet)
 [![Build Status](https://secure.travis-ci.org/google/signet.png)](http://travis-ci.org/google/signet)
-[![Dependency Status](https://gemnasium.com/google/signet.png)](https://gemnasium.com/google/signet)
 
 ## Description
 
diff --git a/lib/signet/oauth_2/client.rb b/lib/signet/oauth_2/client.rb
index 1e58ae4..13e57a5 100644
--- a/lib/signet/oauth_2/client.rb
+++ b/lib/signet/oauth_2/client.rb
@@ -95,7 +95,6 @@ def initialize(options={})
         @client_secret        = nil
         @code                 = nil
         @expires_at           = nil
-        @expires_in           = nil
         @issued_at            = nil
         @issuer               = nil
         @password             = nil
@@ -723,32 +722,37 @@ def decoded_id_token(public_key=nil, options = {}, &keyfinder)
 
       ##
       # Returns the lifetime of the access token in seconds.
+      # Returns nil if the token does not expire.
       #
-      # @return [Integer] The access token lifetime.
+      # @return [Integer, nil] The access token lifetime.
       def expires_in
-        return @expires_in
+        if @expires_at.nil? || @issued_at.nil?
+          nil
+        else
+          (@expires_at - @issued_at).to_i
+        end
       end
 
       ##
-      # Sets the lifetime of the access token in seconds.  Resets the issued
-      # timestamp.
+      # Sets the lifetime of the access token in seconds.  Resets the issued_at
+      # timestamp. Nil values will be treated as though the token does
+      # not expire.
       #
-      # @param [String, Integer] new_expires_in
+      # @param [String, Integer, nil] new_expires_in
       #   The access token lifetime.
       def expires_in=(new_expires_in)
         if new_expires_in != nil
-          @expires_in = new_expires_in.to_i
           @issued_at = Time.now
+          @expires_at = @issued_at + new_expires_in.to_i
         else
-          @expires_in, @issued_at = nil, nil
+          @expires_at, @issued_at = nil, nil
         end
-        @expires_at = nil
       end
 
       ##
       # Returns the timestamp the access token was issued at.
       #
-      # @return [Time] The access token issuance time.
+      # @return [Time, nil] The access token issuance time.
       def issued_at
         return @issued_at
       end
@@ -764,29 +768,26 @@ def issued_at=(new_issued_at)
 
       ##
       # Returns the timestamp the access token will expire at.
+      # Returns nil if the token does not expire. 
       #
-      # @return [Time] The access token lifetime.
+      # @return [Time, nil] The access token lifetime.
       def expires_at
-        if @expires_at
-          @expires_at
-        elsif @issued_at && @expires_in
-          return @issued_at + @expires_in
-        else
-          return nil
-        end
+        @expires_at
       end
 
       ##
       # Limits the lifetime of the access token as number of seconds since
-      # the Epoch
-      # @param [String,Integer,Time] new_expires_at
-      #    The access token issuance time.
+      # the Epoch. Nil values will be treated as though the token does
+      # not expire.
+      # @param [String,Integer,Time, nil] new_expires_at
+      #    The access token expiration time.
       def expires_at=(new_expires_at)
-        @expires_at = normalize_timestamp(new_expires_at)
+        @expires_at = normalize_timestamp new_expires_at
       end
 
       ##
       # Returns true if the access token has expired.
+      # Returns false if the token has not expired or has an nil @expires_at.
       #
       # @return [TrueClass, FalseClass]
       #   The expiration state of the access token.
@@ -796,7 +797,7 @@ def expired?
 
       ##
       # Returns true if the access token has expired or expires within
-      # the next n seconds
+      # the next n seconds. Returns false for tokens with a nil @expires_at.
       #
       # @param [Integer] sec
       #  Max number of seconds from now where a token is still considered
@@ -817,7 +818,7 @@ def clear_credentials!
         @password = nil
         @code = nil
         @issued_at = nil
-        @expires_in = nil
+        @expires_at = nil
       end
 
 
@@ -1006,8 +1007,6 @@ def fetch_access_token(options={})
       end
 
       def fetch_access_token!(options={})
-        options = deep_hash_normalize(options)
-
         token_hash = self.fetch_access_token(options)
         if token_hash
           # No-op for grant types other than `authorization_code`.
@@ -1023,8 +1022,6 @@ def fetch_access_token!(options={})
       ##
       # Refresh the access token, if possible
       def refresh!(options={})
-        options = deep_hash_normalize(options)
-
         self.fetch_access_token!(options)
       end
 
diff --git a/lib/signet/version.rb b/lib/signet/version.rb
index ec03143..6ed1c07 100644
--- a/lib/signet/version.rb
+++ b/lib/signet/version.rb
@@ -17,8 +17,8 @@
   module Signet
     module VERSION
       MAJOR = 0
-      MINOR = 8
-      TINY  = 1
+      MINOR = 9
+      TINY  = 0
       PRE   = nil
 
       STRING = [MAJOR, MINOR, TINY, PRE].compact.join('.')
diff --git a/spec/signet/oauth_2/client_spec.rb b/spec/signet/oauth_2/client_spec.rb
index bfd0b8a..35b8966 100644
--- a/spec/signet/oauth_2/client_spec.rb
+++ b/spec/signet/oauth_2/client_spec.rb
@@ -442,9 +442,38 @@ def build_form_encoded_response(payload)
     expect(@client).to_not be_expired
   end
 
+  it 'should set expires_in when expires_at is set' do
+    issued_at = Time.now
+    expires_at = Time.now+100
+    @client.expires_at = expires_at.to_i
+    @client.issued_at = issued_at
+    expect(@client.expires_in).to be_within(1).of (expires_at - issued_at).to_i
+    @client.expires_at = nil
+    expect(@client.expires_in).to be_nil
+  end
+
+  it 'should set expires_in to nil when expires_at is set to nil' do
+    @client.expires_at = nil
+    expect(@client.expires_in).to be_nil
+  end
+
+  it 'should set expires_at when expires_in is set' do
+    expires_in = 100
+    @client.expires_in = expires_in
+    expect(@client.expires_at).to eq (@client.issued_at + expires_in)
+    @client.expires_in = nil
+    expect(@client.expires_at).to be_nil
+  end
+
+  it 'should set expires_at to nil when expires_in is set to nil' do
+    @client.expires_in = nil
+    expect(@client.expires_at).to be_nil
+  end
+
   it 'should indicate the token is not expired if expired_at nil' do
     @client.expires_at = nil
     expect(@client.expires_within?(60)).to be false
+    expect(@client.expired?).to be false
   end
 
   it 'should indicate the token is not expiring when expiry beyond window' do
@@ -880,7 +909,7 @@ def build_form_encoded_response(payload)
   end
 
   it 'should raise an error if the id token cannot be verified' do
-    pending "Need to update test data"
+    pending "Need to set test data"
     @client.client_id = 'client-12345'
     @client.client_secret = 'secret-12345'
     stubs = Faraday::Adapter::Test::Stubs.new do |stub|