diff --git a/lib/faraday/connection.rb b/lib/faraday/connection.rb
index 6316fc93..e979e828 100644
--- a/lib/faraday/connection.rb
+++ b/lib/faraday/connection.rb
@@ -473,7 +473,8 @@ def build_exclusive_url(url = nil, params = nil, params_encoder = nil)
       if url && !base.path.end_with?('/')
         base.path = "#{base.path}/" # ensure trailing slash
       end
-      url = url.to_s.gsub(':', '%3A') if URI.parse(url.to_s).opaque
+      # Ensure relative url will be parsed correctly (such as `service:search` )
+      url = "./#{url}" if url.respond_to?(:start_with?) && !url.start_with?('http://', 'https://', '/', './', '../')
       uri = url ? base + url : base
       if params
         uri.query = params.to_query(params_encoder || options.params_encoder)
diff --git a/spec/faraday/connection_spec.rb b/spec/faraday/connection_spec.rb
index d4ccb23d..7fa726a4 100644
--- a/spec/faraday/connection_spec.rb
+++ b/spec/faraday/connection_spec.rb
@@ -300,14 +300,14 @@ def decode(params)
       it 'joins url to base when used relative path' do
         conn = Faraday.new(url: url)
         uri = conn.build_exclusive_url('service:search?limit=400')
-        expect(uri.to_s).to eq('http://service.com/service%3Asearch?limit=400')
+        expect(uri.to_s).to eq('http://service.com/service:search?limit=400')
       end
 
       it 'joins url to base when used with path prefix' do
         conn = Faraday.new(url: url)
         conn.path_prefix = '/api'
         uri = conn.build_exclusive_url('service:search?limit=400')
-        expect(uri.to_s).to eq('http://service.com/api/service%3Asearch?limit=400')
+        expect(uri.to_s).to eq('http://service.com/api/service:search?limit=400')
       end
     end