diff --git a/lib/sassc/embedded.rb b/lib/sassc/embedded.rb
index 5566243..d2d8195 100644
--- a/lib/sassc/embedded.rb
+++ b/lib/sassc/embedded.rb
@@ -3,7 +3,6 @@
 require 'sassc'
 require 'sass-embedded'
 
-require 'base64'
 require 'json'
 require 'uri'
 
@@ -46,7 +45,7 @@ def render
       unless @source_map.nil? || omit_source_map_url?
         url = URL.parse(output_url || file_url)
         source_mapping_url = if source_map_embed?
-                               "data:application/json;base64,#{Base64.strict_encode64(@source_map)}"
+                               "data:application/json;base64,#{[@source_map].pack('m0')}"
                              else
                                URL.parse(source_map_file_url).route_from(url).to_s
                              end
diff --git a/sassc-embedded.gemspec b/sassc-embedded.gemspec
index 81dfa9e..d3b375e 100644
--- a/sassc-embedded.gemspec
+++ b/sassc-embedded.gemspec
@@ -24,7 +24,6 @@ Gem::Specification.new do |spec| # rubocop:disable Gemspec/RequireMFA
 
   spec.required_ruby_version = '>= 3.0.0'
 
-  spec.add_runtime_dependency 'base64', '~> 0.1'
   spec.add_runtime_dependency 'sassc', '~> 2.0'
   spec.add_runtime_dependency 'sass-embedded', '~> 1.64'
 end