diff --git a/sinatra-contrib/sinatra-contrib.gemspec b/sinatra-contrib/sinatra-contrib.gemspec
index e969e3e4..eeb67ce3 100644
--- a/sinatra-contrib/sinatra-contrib.gemspec
+++ b/sinatra-contrib/sinatra-contrib.gemspec
@@ -37,7 +37,7 @@ EOF
   s.required_ruby_version = '>= 2.3.0'
 
   s.add_dependency "sinatra", version
-  s.add_dependency "mustermann", "~> 1.0"
+  s.add_dependency "mustermann", "~> 2.0"
   s.add_dependency "tilt", "~> 2.0"
   s.add_dependency "rack-protection", version
   s.add_dependency "multi_json"
diff --git a/sinatra.gemspec b/sinatra.gemspec
index 46c23f77..cfa4324c 100644
--- a/sinatra.gemspec
+++ b/sinatra.gemspec
@@ -45,5 +45,5 @@ EOF
   s.add_dependency 'rack', '~> 2.2'
   s.add_dependency 'tilt', '~> 2.0'
   s.add_dependency 'rack-protection', version
-  s.add_dependency 'mustermann', '~> 1.0'
+  s.add_dependency 'mustermann', '~> 2.0'
 end