diff --git a/src/service.cr b/src/service.cr
index 23da9ae..ae0ddcd 100644
--- a/src/service.cr
+++ b/src/service.cr
@@ -79,6 +79,8 @@ commands.push "add", "Adds a service to an environment." do |args|
 				provider = service.get_default_provider token.token
 			end
 
+			next if provider.nil? && token.optional
+
 			if provider.nil?
 				STDERR.puts "This service consumes a “#{token.token}” token, but you have not specified what other service is supposed to provide it."
 				STDERR.puts "Use the `service add #{args[1]} #{token.token}=<provider>` syntax to specify it."
diff --git a/src/service/service_definition.cr b/src/service/service_definition.cr
index bf1e53e..e99711b 100644
--- a/src/service/service_definition.cr
+++ b/src/service/service_definition.cr
@@ -4,6 +4,7 @@ require "specparser"
 class ServiceDefinition
 	struct Consumes
 		getter token : String
+		getter optional : Bool
 		def initialize(@token)
 			@optional = false