diff --git a/lib/avatax/connection.rb b/lib/avatax/connection.rb
index 385fad1..04e47bd 100644
--- a/lib/avatax/connection.rb
+++ b/lib/avatax/connection.rb
@@ -4,7 +4,7 @@ module AvaTax
 
   module Connection
     private
-    AUTHORIZATION_FILTER_REGEX = /(Authorization\:\ \"Basic\ )(\w+)\=/
+    AUTHORIZATION_FILTER_REGEX = /(Authorization\:\ \"Basic\ )(\w+\=*)/
     REMOVED_LABEL = '\1[REMOVED]'
 
     def connection
diff --git a/spec/avatax/connection_spec.rb b/spec/avatax/connection_spec.rb
new file mode 100644
index 0000000..1244f48
--- /dev/null
+++ b/spec/avatax/connection_spec.rb
@@ -0,0 +1,42 @@
+require File.expand_path('../../spec_helper', __FILE__)
+
+describe AvaTax::Connection do
+  describe "AUTHORIZATION_FILTER_REGEX" do
+    let(:message) do
+      <<EOS
+Accept: "application/json; charset=utf-8"
+User-Agent: "AvaTax Ruby Gem 19.7.0"
+X-Avalara-Client: ";;RubySdk;19.7.0;"
+Authorization: "Basic #{encoded_token}"
+Content-Type: "application/json"
+EOS
+    end
+
+    context "a base 64 encoded value ending with =" do
+      let(:encoded_token) { "YmFzZTY0cGFzc3dvcmQuUmVhbGx5Pwo=" }
+
+      it "should match regex" do
+        expect(message).to match(described_class::AUTHORIZATION_FILTER_REGEX)
+      end
+
+      it "should capture the whole auth token" do
+        groups = message.match(described_class::AUTHORIZATION_FILTER_REGEX)
+        expect(groups[2]).to eq(encoded_token)
+      end
+    end
+
+    context "a base 64 encoded value NOT ending with =" do
+      let(:encoded_token) { "bm9hcGlrZXlpbjIwMTkK" }
+
+      it "should match regex" do
+        expect(message).to match(described_class::AUTHORIZATION_FILTER_REGEX)
+      end
+
+      it "should capture the whole auth token" do
+        groups = message.match(described_class::AUTHORIZATION_FILTER_REGEX)
+        expect(groups[2]).to eq(encoded_token)
+      end
+    end
+  end
+end
+