diff --git a/lib/gitlab/ldap/config.rb b/lib/gitlab/ldap/config.rb
index af0d743f4d..697b66dcda 100644
--- a/lib/gitlab/ldap/config.rb
+++ b/lib/gitlab/ldap/config.rb
@@ -17,8 +17,8 @@ module Gitlab
       end
 
       def initialize(provider)
-        raise "Unknown provider (#{provider}). Available providers: #{self.class.providers}"
         @provider = provider
+        invalid_provider unless valid_provider?
         @options = config_for(provider)
       end
 
@@ -89,6 +89,14 @@ module Gitlab
         end
       end
 
+      def valid_provider?
+        self.class.providers.include?(provider)
+      end
+
+      def invalid_provider
+        raise "Unknown provider (#{provider}). Available providers: #{self.class.providers}"
+      end
+
       def auth_options
         {
           auth: {
diff --git a/spec/lib/gitlab/ldap/config_spec.rb b/spec/lib/gitlab/ldap/config_spec.rb
index a01166b264..76cc7f95c4 100644
--- a/spec/lib/gitlab/ldap/config_spec.rb
+++ b/spec/lib/gitlab/ldap/config_spec.rb
@@ -12,5 +12,9 @@ describe Gitlab::LDAP::Config do
     it "works" do
       expect(config).to be_a described_class
     end
+
+    it "raises an error if a unknow provider is used" do
+      expect{ Gitlab::LDAP::Config.new 'unknown' }.to raise_error
+    end
   end
 end
\ No newline at end of file