diff --git a/lib/onelogin/ruby-saml/authrequest.rb b/lib/onelogin/ruby-saml/authrequest.rb
index 870219a56..443750f90 100644
--- a/lib/onelogin/ruby-saml/authrequest.rb
+++ b/lib/onelogin/ruby-saml/authrequest.rb
@@ -36,6 +36,7 @@ def create(settings, params = {})
         params.each_pair do |key, value|
           request_params << "&#{key.to_s}=#{CGI.escape(value.to_s)}"
         end
+        raise "Invalid settings, idp_sso_target_url is not set!" if settings.idp_sso_target_url.nil?
         @login_url = settings.idp_sso_target_url + request_params
       end
 
diff --git a/test/request_test.rb b/test/request_test.rb
index 379a11033..239e73737 100644
--- a/test/request_test.rb
+++ b/test/request_test.rb
@@ -129,6 +129,19 @@ class RequestTest < Minitest::Test
       assert_match /&hello=$/, auth_url
     end
 
+    describe "when the target url is not set" do
+      before do
+        settings.idp_sso_target_url = nil
+      end
+
+      it "raises an error with a descriptive message" do
+        err = assert_raises RuntimeError do
+          OneLogin::RubySaml::Authrequest.new.create(settings)
+        end
+        assert_match /idp_sso_target_url is not set/, err.message
+      end
+    end
+
     describe "when the target url doesn't contain a query string" do
       it "create the SAMLRequest parameter correctly" do