diff --git a/spec/ameba/rule/lint/useless_assign_spec.cr b/spec/ameba/rule/lint/useless_assign_spec.cr
index 79d6619f..5ee62329 100644
--- a/spec/ameba/rule/lint/useless_assign_spec.cr
+++ b/spec/ameba/rule/lint/useless_assign_spec.cr
@@ -228,7 +228,7 @@ module Ameba::Rule::Lint
     it "does not report if global var" do
       s = Source.new %(
         def method
-          $? = 3
+          $1 = 3
         end
       )
       subject.catch(s).should be_valid
diff --git a/spec/ameba/rule/performance/size_after_filter_spec.cr b/spec/ameba/rule/performance/size_after_filter_spec.cr
index bfd67336..ccf958d8 100644
--- a/spec/ameba/rule/performance/size_after_filter_spec.cr
+++ b/spec/ameba/rule/performance/size_after_filter_spec.cr
@@ -66,8 +66,8 @@ module Ameba::Rule::Performance
       issue = s.issues.first
 
       issue.rule.should_not be_nil
-      issue.location.to_s.should eq "source.cr:1:4"
-      issue.end_location.to_s.should eq "source.cr:1:25"
+      issue.location.to_s.should eq "source.cr:2:4"
+      issue.end_location.to_s.should eq "source.cr:2:25"
       issue.message.should eq "Use `count {...}` instead of `reject {...}.size`."
     end
   end
diff --git a/src/ameba/ast/util.cr b/src/ameba/ast/util.cr
index 32a83b2a..091ba00f 100644
--- a/src/ameba/ast/util.cr
+++ b/src/ameba/ast/util.cr
@@ -56,12 +56,12 @@ module Ameba::AST::Util
   # Returns true if node is a flow command, false - otherwise.
   # Node represents a flow command if it is a control expression,
   # or special call node that interrupts execution (i.e. raise, exit, abort).
-  def flow_command?(node, in_loop?)
+  def flow_command?(node, in_loop)
     case node
     when Crystal::Return
       true
     when Crystal::Break, Crystal::Next
-      in_loop?
+      in_loop
     when Crystal::Call
       raise?(node) || exit?(node) || abort?(node)
     else
@@ -95,31 +95,31 @@ module Ameba::AST::Util
   #
   # That's because not all branches return(i.e. `else` is missing).
   #
-  def flow_expression?(node, in_loop? = false)
-    return true if flow_command? node, in_loop?
+  def flow_expression?(node, in_loop = false)
+    return true if flow_command? node, in_loop
 
     case node
     when Crystal::If, Crystal::Unless
-      flow_expressions? [node.then, node.else], in_loop?
+      flow_expressions? [node.then, node.else], in_loop
     when Crystal::BinaryOp
-      flow_expression? node.left, in_loop?
+      flow_expression? node.left, in_loop
     when Crystal::Case
-      flow_expressions? [node.whens, node.else].flatten, in_loop?
+      flow_expressions? [node.whens, node.else].flatten, in_loop
     when Crystal::ExceptionHandler
-      flow_expressions? [node.else || node.body, node.rescues].flatten, in_loop?
+      flow_expressions? [node.else || node.body, node.rescues].flatten, in_loop
     when Crystal::While, Crystal::Until
-      flow_expression? node.body, in_loop?
+      flow_expression? node.body, in_loop
     when Crystal::Rescue, Crystal::When
-      flow_expression? node.body, in_loop?
+      flow_expression? node.body, in_loop
     when Crystal::Expressions
-      node.expressions.any? { |exp| flow_expression? exp, in_loop? }
+      node.expressions.any? { |exp| flow_expression? exp, in_loop }
     else
       false
     end
   end
 
-  private def flow_expressions?(nodes, in_loop?)
-    nodes.all? { |exp| flow_expression? exp, in_loop? }
+  private def flow_expressions?(nodes, in_loop)
+    nodes.all? { |exp| flow_expression? exp, in_loop }
   end
 
   # Returns true if node represents `raise` method call.
diff --git a/src/ameba/config.cr b/src/ameba/config.cr
index d3c72040..d82c26af 100644
--- a/src/ameba/config.cr
+++ b/src/ameba/config.cr
@@ -50,8 +50,8 @@ class Ameba::Config
   # config = Ameba::Config.load
   # ```
   #
-  def self.load(path = PATH, colors? = true)
-    Colorize.enabled = colors?
+  def self.load(path = PATH, colors = true)
+    Colorize.enabled = colors
     content = File.exists?(path) ? File.read path : ""
     Config.new YAML.parse(content)
   rescue e
diff --git a/src/ameba/formatter/dot_formatter.cr b/src/ameba/formatter/dot_formatter.cr
index b8b57ca1..6cf51631 100644
--- a/src/ameba/formatter/dot_formatter.cr
+++ b/src/ameba/formatter/dot_formatter.cr
@@ -10,7 +10,7 @@ module Ameba::Formatter
 
     # Reports a message when inspection is started.
     def started(sources)
-      @started_at = Time.now # Time.monotonic
+      @started_at = Time.utc # Time.monotonic
 
       output << started_message(sources.size)
     end
@@ -45,7 +45,7 @@ module Ameba::Formatter
         end
       end
 
-      output << finished_in_message(@started_at, Time.now) # Time.monotonic
+      output << finished_in_message(@started_at, Time.utc) # Time.monotonic
       output << final_message(sources, failed_sources)
     end
 
diff --git a/src/ameba/formatter/todo_formatter.cr b/src/ameba/formatter/todo_formatter.cr
index 857b42b6..e127d657 100644
--- a/src/ameba/formatter/todo_formatter.cr
+++ b/src/ameba/formatter/todo_formatter.cr
@@ -41,7 +41,7 @@ module Ameba::Formatter
     private def header
       <<-HEADER
         # This configuration file was generated by `ameba --gen-config`
-        # on #{Time.utc_now} using Ameba version #{VERSION}.
+        # on #{Time.utc} using Ameba version #{VERSION}.
         # The point is for the user to remove these configuration records
         # one by one as the reported problems are removed from the code base.
 
diff --git a/src/ameba/inline_comments.cr b/src/ameba/inline_comments.cr
index 5aea7cfc..3dcaf97d 100644
--- a/src/ameba/inline_comments.cr
+++ b/src/ameba/inline_comments.cr
@@ -94,11 +94,11 @@ module Ameba
     end
 
     private def commented_out?(line)
-      commented? = false
+      commented = false
 
       lexer = Crystal::Lexer.new(line).tap { |l| l.comments_enabled = true }
-      Tokenizer.new(lexer).run { |t| commented? = true if t.type == :COMMENT }
-      commented?
+      Tokenizer.new(lexer).run { |t| commented = true if t.type == :COMMENT }
+      commented
     end
   end
 end
diff --git a/src/ameba/rule/lint/comparison_to_boolean.cr b/src/ameba/rule/lint/comparison_to_boolean.cr
index 3e595b51..f9a314c6 100644
--- a/src/ameba/rule/lint/comparison_to_boolean.cr
+++ b/src/ameba/rule/lint/comparison_to_boolean.cr
@@ -33,11 +33,11 @@ module Ameba::Rule::Lint
     end
 
     def test(source, node : Crystal::Call)
-      comparison? = %w(== != ===).includes?(node.name)
-      to_boolean? = node.args.first?.try &.is_a?(Crystal::BoolLiteral) ||
-                    node.obj.is_a?(Crystal::BoolLiteral)
+      comparison = %w(== != ===).includes?(node.name)
+      to_boolean = node.args.first?.try &.is_a?(Crystal::BoolLiteral) ||
+                   node.obj.is_a?(Crystal::BoolLiteral)
 
-      return unless comparison? && to_boolean?
+      return unless comparison && to_boolean
 
       issue_for node, MSG
     end
diff --git a/src/ameba/rule/style/method_names.cr b/src/ameba/rule/style/method_names.cr
index 5d424c4b..7ffd37f5 100644
--- a/src/ameba/rule/style/method_names.cr
+++ b/src/ameba/rule/style/method_names.cr
@@ -53,9 +53,9 @@ module Ameba::Rule::Style
       return if (expected = node.name.underscore) == node.name
 
       line_number = node.location.try &.line_number
-      column_number = node.name_column_number
+      column_number = node.name_location.try &.column_number
 
-      return unless line_number
+      return if line_number.nil? || column_number.nil?
 
       issue_for(
         {line_number, column_number},
diff --git a/src/ameba/rule/style/redundant_begin.cr b/src/ameba/rule/style/redundant_begin.cr
index e21d1927..891da8e2 100644
--- a/src/ameba/rule/style/redundant_begin.cr
+++ b/src/ameba/rule/style/redundant_begin.cr
@@ -108,7 +108,7 @@ module Ameba::Rule::Style
 
     private def def_redundant_begin?(code)
       lexer = Crystal::Lexer.new code
-      in_body? = in_argument_list? = false
+      in_body = in_argument_list = false
       loop do
         token = lexer.next_token
 
@@ -116,16 +116,16 @@ module Ameba::Rule::Style
         when :EOF, :"->"
           break
         when :IDENT
-          return token.value == :begin if in_body?
+          return token.value == :begin if in_body
         when :"("
-          in_argument_list? = true
+          in_argument_list = true
         when :")"
-          in_argument_list? = false
+          in_argument_list = false
         when :NEWLINE
-          in_body? = true unless in_argument_list?
+          in_body = true unless in_argument_list
         when :SPACE
         else
-          return false if in_body?
+          return false if in_body
         end
       end
     end