diff --git a/lib/adyen/client.rb b/lib/adyen/client.rb
index e3545c6..493edcc 100644
--- a/lib/adyen/client.rb
+++ b/lib/adyen/client.rb
@@ -22,7 +22,7 @@ def initialize(ws_user: nil, ws_password: nil, api_key: nil, oauth_token: nil, e
       @ws_password = ws_password
       @api_key = api_key
       @oauth_token = oauth_token
-      @env = env
+      self.env = env
       @application_name = application_name
       @adapter = adapter || Faraday.default_adapter
       if Gem::Version.new(Faraday::VERSION) >= Gem::Version.new('2.1')
@@ -33,7 +33,7 @@ def initialize(ws_user: nil, ws_password: nil, api_key: nil, oauth_token: nil, e
         @adapter_options = adapter_options || {}
       end
       @mock_service_url_base = mock_service_url_base || "http://localhost:#{mock_port}"
-      @live_url_prefix = live_url_prefix
+      self.live_url_prefix = live_url_prefix
       if RUBY_VERSION >= '3.2'
         # set default timeouts
         @connection_options = connection_options || Faraday::ConnectionOptions.new(
@@ -60,7 +60,9 @@ def env=(value)
 
     # remove 'https' from live_url_prefix if necessary
     def live_url_prefix=(value)
-      value['https://'] = '' unless value['https://'].nil?
+      unless value.nil?
+        value['https://'] = '' unless value['https://'].nil?
+      end
       @live_url_prefix = value
     end
 
diff --git a/spec/client_spec.rb b/spec/client_spec.rb
index 433766b..830e54b 100644
--- a/spec/client_spec.rb
+++ b/spec/client_spec.rb
@@ -18,6 +18,22 @@
       .to eq(:test)
   end
 
+  it 'raises ArgumentError when initialized with an invalid env string' do
+    expect { Adyen::Client.new(env: 'live') }
+      .to raise_error(ArgumentError)
+  end
+
+  it 'raises ArgumentError when initialized with an invalid env value' do
+    expect { Adyen::Client.new(env: :invalid) }
+      .to raise_error(ArgumentError)
+  end
+
+  it 'strips https:// from live_url_prefix when passed via constructor' do
+    client = Adyen::Client.new(env: :live, live_url_prefix: 'https://myprefix')
+    expect(client.service_url_base('Payment'))
+      .to eq('https://myprefix-pal-live.adyenpayments.com/pal/servlet/Payment')
+  end
+
   it 'sets the version number' do
     @shared_values[:client].checkout.version = @shared_values[:version]
     expect(@shared_values[:client].checkout.version)