diff --git a/README.md b/README.md
index c7fd2ec..2e7d159 100644
--- a/README.md
+++ b/README.md
@@ -44,17 +44,17 @@ Ronin::DNS::Proxy.run('127.0.0.1', 2346) do |server|
   server.add_rule :A, 'updates.example.com', :ServFail
 
   # define a dynamic rule
-  server.add_rule :CNAME, /^www\./, ->(type,name,transaction) {
+  server.add_rule(:CNAME, /^www\./) do |type,name,transaction|
     # append '.hax' to the domain name
     names = name.split('.').push('hax')
 
     transaction.respond!(names)
-  }
+  end
 
   # return MX records
-  server.add_rule :MX, 'example.com', ->(type,name,transaction) {
+  server.add_rule(:MX, 'example.com') do |type,name,transaction|
     transaction.respond!(10, Resolv::DNS::Name.create('email.evil.com' ))
-  }
+  end
 end
 ```
 
diff --git a/lib/ronin/dns/proxy/rule.rb b/lib/ronin/dns/proxy/rule.rb
index 5da703f..9de2368 100644
--- a/lib/ronin/dns/proxy/rule.rb
+++ b/lib/ronin/dns/proxy/rule.rb
@@ -55,10 +55,30 @@ class Rule
         # @param [String, Array<String>, Symbol, #call] result
         #   The result to return.
         #
-        def initialize(type,name,result)
+        # @yield [type, name, transaction]
+        #   If no result argument is given, the given block will be passed the
+        #   DNS query's type, name, and transaction object.
+        #
+        # @yieldparam [Symbol] type
+        #   The query type.
+        #
+        # @yieldparam [String] name
+        #   The queried host name.
+        #
+        # @yieldparam [Async::DNS::Transaction] transaction
+        #   The DNS query transaction object.
+        #
+        # @raise [ArgumentError]
+        #   Must specify a `result` argument or a block.
+        #
+        def initialize(type,name,result=nil,&block)
+          unless (result || block)
+            raise(ArgumentError,"must specify a result value or a block")
+          end
+
           @type   = type
           @name   = name
-          @result = result
+          @result = result || block
         end
 
         #
diff --git a/lib/ronin/dns/proxy/server.rb b/lib/ronin/dns/proxy/server.rb
index 837ecdd..651e086 100644
--- a/lib/ronin/dns/proxy/server.rb
+++ b/lib/ronin/dns/proxy/server.rb
@@ -117,7 +117,7 @@ def initialize(host,port, nameservers: Ronin::Support::Network::DNS.nameservers,
         # @param [String, Regexp] name
         #   The record name that the rule will match against.
         #
-        # @param [String, Array<String>, Symbol, Proc<Symbol, String, Async::DNS::Transaction>] result
+        # @param [String, Array<String>, Symbol, #call] result
         #   The result to respond with. It can be a String, or an Array of
         #   Strings, or an error code:
         #
@@ -129,8 +129,18 @@ def initialize(host,port, nameservers: Ronin::Support::Network::DNS.nameservers,
         #   * `:Refused` - The operation was refused by the server.
         #   * `:NotAuth` - The server is not authoritive for the zone.
         #
-        #   If a `Proc` is given, then it will be called with the query type,
-        #   query name, and the DNS query transaction object.
+        # @yield [type, name, transaction]
+        #   If no result argument is given, the given block will be passed the
+        #   DNS query's type, name, and transaction object.
+        #
+        # @yieldparam [Symbol] type
+        #   The query type.
+        #
+        # @yieldparam [String] name
+        #   The queried host name.
+        #
+        # @yieldparam [Async::DNS::Transaction] transaction
+        #   The DNS query transaction object.
         #
         # @example override the IP address for a domain:
         #   server.add_rule :A, 'example.com', '10.0.0.42'
@@ -145,17 +155,21 @@ def initialize(host,port, nameservers: Ronin::Support::Network::DNS.nameservers,
         #   server.add_rule :TXT, /^spf\./, "v=spf1 include:10.0.0.1 ~all"
         #
         # @example define a dynamic rule:
-        #   server.add_rule :CNAME, /^www\./, ->(type,name,transaction) {
+        #   server.add_rule(:CNAME, /^www\./) do |type,name,transaction|
         #     # append '.hax' to the domain name
         #     names = name.split('.').push('hax')
         #
         #     transaction.respond!(names)
-        #   }
+        #   end
         #
         # @api public
         #
-        def add_rule(record_type,name,result)
-          @rules << Rule.new(record_type,name,result)
+        def add_rule(record_type,name,result=nil,&block)
+          unless (result || block)
+            raise(ArgumentError,"must specify a result value or a block")
+          end
+
+          @rules << Rule.new(record_type,name,result,&block)
         end
 
         # Mapping of Resolv resource classes to Symbols.
diff --git a/spec/rule_spec.rb b/spec/rule_spec.rb
index 518a439..f9218fb 100644
--- a/spec/rule_spec.rb
+++ b/spec/rule_spec.rb
@@ -20,6 +20,30 @@
     it "must set #result" do
       expect(subject.result).to eq(result)
     end
+
+    context "when no result is given" do
+      context "but a block is given" do
+        let(:block) do
+          proc { |type,name,transaction|
+            transaction.respond!('foo')
+          }
+        end
+
+        subject { described_class.new(type,name,&block) }
+
+        it "must set #result to the block" do
+          expect(subject.result).to be(block)
+        end
+      end
+
+      context "but a block is not given" do
+        it do
+          expect {
+            described_class.new(type,name)
+          }.to raise_error(ArgumentError,"must specify a result value or a block")
+        end
+      end
+    end
   end
 
   describe "#matches?" do
diff --git a/spec/server_spec.rb b/spec/server_spec.rb
index 43ec7f2..50cf374 100644
--- a/spec/server_spec.rb
+++ b/spec/server_spec.rb
@@ -63,16 +63,48 @@
     let(:record_name)   { 'example.com' }
     let(:record_result) { '10.0.0.1' }
 
-    before do
-      subject.add_rule :TXT, 'foo.example.com', '1.2.3.4'
-      subject.add_rule record_type, record_name, record_result
+    context "when type, name, and result arguments are given" do
+      before do
+        subject.add_rule :TXT, 'foo.example.com', '1.2.3.4'
+        subject.add_rule record_type, record_name, record_result
+      end
+
+      it "must append a new Ronin::DNS::Proxy::Rule object to #rules with the type, name, and result arguments" do
+        expect(subject.rules.last).to be_kind_of(Ronin::DNS::Proxy::Rule)
+        expect(subject.rules.last.type).to eq(record_type)
+        expect(subject.rules.last.name).to eq(record_name)
+        expect(subject.rules.last.result).to eq(record_result)
+      end
     end
 
-    it "must append a new Ronin::DNS::Proxy::Rule object to #rules" do
-      expect(subject.rules.last).to be_kind_of(Ronin::DNS::Proxy::Rule)
-      expect(subject.rules.last.type).to eq(record_type)
-      expect(subject.rules.last.name).to eq(record_name)
-      expect(subject.rules.last.result).to eq(record_result)
+    context "when no result argument is given" do
+      context "but a block is given" do
+        let(:block) do
+          proc { |type,name,transaction|
+            transaction.respond!('foo')
+          }
+        end
+
+        before do
+          subject.add_rule :TXT, 'foo.example.com', '1.2.3.4'
+          subject.add_rule(record_type,record_name,&block)
+        end
+
+        it "must set the rule's result to the given block" do
+          expect(subject.rules.last).to be_kind_of(Ronin::DNS::Proxy::Rule)
+          expect(subject.rules.last.type).to eq(record_type)
+          expect(subject.rules.last.name).to eq(record_name)
+          expect(subject.rules.last.result).to be(block)
+        end
+      end
+
+      context "and no block is given" do
+        it do
+          expect {
+            subject.add_rule(record_type,record_name)
+          }.to raise_error(ArgumentError,"must specify a result value or a block")
+        end
+      end
     end
   end