diff --git a/lib/signer.rb b/lib/signer.rb
index 16b9d25..4941355 100644
--- a/lib/signer.rb
+++ b/lib/signer.rb
@@ -65,6 +65,7 @@ def initialize(document, noblanks: true, wss: true, canonicalize_algorithm: :c14
     self.document = Nokogiri::XML(document.to_s) do |config|
       config.noblanks if noblanks
     end
+    self.document.namespace_inheritance = true if self.document.respond_to?(:namespace_inheritance)
     self.digest_algorithm = :sha1
     self.wss = wss
     self.canonicalize_algorithm = canonicalize_algorithm
diff --git a/signer.gemspec b/signer.gemspec
index ad5ca9f..405d6af 100644
--- a/signer.gemspec
+++ b/signer.gemspec
@@ -21,5 +21,5 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency 'rake'
   gem.add_development_dependency 'rspec'
 
-  gem.add_runtime_dependency 'nokogiri', '>= 1.5.1'
+  gem.add_runtime_dependency 'nokogiri', '>= 1.5.1', '!=1.12.3', '!=1.12.2', '!=1.12.1', '!=1.12.0'
 end