diff --git a/spec/ameba/ast_traverse_spec.cr b/spec/ameba/ast/traverse_spec.cr
similarity index 82%
rename from spec/ameba/ast_traverse_spec.cr
rename to spec/ameba/ast/traverse_spec.cr
index 5cec2da3..3c14a9be 100644
--- a/spec/ameba/ast_traverse_spec.cr
+++ b/spec/ameba/ast/traverse_spec.cr
@@ -1,10 +1,10 @@
-require "../spec_helper"
+require "../../spec_helper"
 
-module Ameba
+module Ameba::AST
   rule = DummyRule.new
   source = Source.new ""
 
-  describe "AST Traverse" do
+  describe "Traverse" do
     {% for name in NODE_VISITORS %}
       describe "{{name}}" do
         it "allow to visit {{name}} node" do
diff --git a/spec/ameba/ast/util_spec.cr b/spec/ameba/ast/util_spec.cr
new file mode 100644
index 00000000..08bd3497
--- /dev/null
+++ b/spec/ameba/ast/util_spec.cr
@@ -0,0 +1,39 @@
+require "../../spec_helper"
+
+module Ameba::AST
+  struct Test
+    include Util
+  end
+
+  subject = Test.new
+
+  describe Util do
+    describe "#literal?" do
+      [
+        Crystal::ArrayLiteral.new,
+        Crystal::BoolLiteral.new(false),
+        Crystal::CharLiteral.new('a'),
+        Crystal::HashLiteral.new,
+        Crystal::NamedTupleLiteral.new,
+        Crystal::NilLiteral.new,
+        Crystal::NumberLiteral.new(42),
+        Crystal::RegexLiteral.new(Crystal::NilLiteral.new),
+        Crystal::StringLiteral.new(""),
+        Crystal::SymbolLiteral.new(""),
+        Crystal::TupleLiteral.new([] of Crystal::ASTNode),
+        Crystal::RangeLiteral.new(
+          Crystal::NilLiteral.new,
+          Crystal::NilLiteral.new,
+          true),
+      ].each do |literal|
+        it "returns true if node is #{literal}" do
+          subject.literal?(literal).should be_true
+        end
+      end
+
+      it "returns false if node is not a literal" do
+        subject.literal?(Crystal::Nop).should be_false
+      end
+    end
+  end
+end
diff --git a/src/ameba.cr b/src/ameba.cr
index 5caa690a..043b4846 100644
--- a/src/ameba.cr
+++ b/src/ameba.cr
@@ -1,4 +1,5 @@
 require "./ameba/*"
+require "./ameba/ast/*"
 require "./ameba/rules/*"
 
 module Ameba
diff --git a/src/ameba/ast_traverse.cr b/src/ameba/ast/traverse.cr
similarity index 96%
rename from src/ameba/ast_traverse.cr
rename to src/ameba/ast/traverse.cr
index b4a06c74..6b3554fa 100644
--- a/src/ameba/ast_traverse.cr
+++ b/src/ameba/ast/traverse.cr
@@ -1,6 +1,6 @@
 require "compiler/crystal/syntax/*"
 
-module Ameba
+module Ameba::AST
   NODE_VISITORS = [
     Call,
     Case,
diff --git a/src/ameba/ast/util.cr b/src/ameba/ast/util.cr
new file mode 100644
index 00000000..6e6b4970
--- /dev/null
+++ b/src/ameba/ast/util.cr
@@ -0,0 +1,5 @@
+module Ameba::AST::Util
+  def literal?(node)
+    node.try &.class.name.ends_with? "Literal"
+  end
+end
diff --git a/src/ameba/rules/comparison_to_boolean.cr b/src/ameba/rules/comparison_to_boolean.cr
index 3d4e61c0..e76df2cf 100644
--- a/src/ameba/rules/comparison_to_boolean.cr
+++ b/src/ameba/rules/comparison_to_boolean.cr
@@ -13,7 +13,7 @@ module Ameba::Rules
   # or negating the variable.
   struct ComparisonToBoolean < Rule
     def test(source)
-      CallVisitor.new self, source
+      AST::CallVisitor.new self, source
     end
 
     def test(source, node : Crystal::Call)
diff --git a/src/ameba/rules/literal_in_condition.cr b/src/ameba/rules/literal_in_condition.cr
index 7dfae7e7..033f79d8 100644
--- a/src/ameba/rules/literal_in_condition.cr
+++ b/src/ameba/rules/literal_in_condition.cr
@@ -13,10 +13,12 @@ module Ameba::Rules
   # end
   # ```
   struct LiteralInCondition < Rule
+    include AST::Util
+
     def test(source)
-      IfVisitor.new self, source
-      UnlessVisitor.new self, source
-      CaseVisitor.new self, source
+      AST::IfVisitor.new self, source
+      AST::UnlessVisitor.new self, source
+      AST::CaseVisitor.new self, source
     end
 
     def check_node(source, node)
@@ -36,9 +38,5 @@ module Ameba::Rules
     def test(source, node : Crystal::Case)
       check_node source, node
     end
-
-    private def literal?(node)
-      node.try &.class.name.ends_with? "Literal"
-    end
   end
 end
diff --git a/src/ameba/rules/unless_else.cr b/src/ameba/rules/unless_else.cr
index 3a60766f..148b3b12 100644
--- a/src/ameba/rules/unless_else.cr
+++ b/src/ameba/rules/unless_else.cr
@@ -37,7 +37,7 @@ module Ameba::Rules
   # ```
   struct UnlessElse < Rule
     def test(source)
-      UnlessVisitor.new self, source
+      AST::UnlessVisitor.new self, source
     end
 
     def test(source, node : Crystal::Unless)