diff --git a/shard.yml b/shard.yml
index 2f8ca60..5e8cc7a 100644
--- a/shard.yml
+++ b/shard.yml
@@ -11,4 +11,4 @@ license: MIT
 development_dependencies:
   ameba:
     github: crystal-ameba/ameba
-    version: ~> 1.0.0
+    version: ~> 1.5.0
diff --git a/spec/lucky_task/runner_spec.cr b/spec/lucky_task/runner_spec.cr
index 334fbf9..fe2fe59 100644
--- a/spec/lucky_task/runner_spec.cr
+++ b/spec/lucky_task/runner_spec.cr
@@ -4,9 +4,10 @@ include HaveDefaultHelperMessageMatcher
 
 describe LuckyTask::Runner do
   it "adds tasks to the runner when task classes are created" do
-    expected_task_names = ["another_task", "my.cool_task", "my.custom_name"]
+    expected_task_names = ["another_task", "my.cool_task", "my.custom_name", "task_with_args", "task_with_required_format_args", "task_with_switch_flags", "task_with_int32_flags", "task_with_float64_flags", "task_with_positional_args", "task_with_fancy_output"]
 
     task_names = LuckyTask::Runner.tasks.map(&.name)
+    task_names.size.should eq(expected_task_names.size)
 
     expected_task_names.each do |expected_task_name|
       task_names.should contain(expected_task_name)
diff --git a/spec/lucky_task/task_spec.cr b/spec/lucky_task/task_spec.cr
index 2361fe6..ca320f4 100644
--- a/spec/lucky_task/task_spec.cr
+++ b/spec/lucky_task/task_spec.cr
@@ -44,24 +44,24 @@ describe LuckyTask::Task do
 
   describe "with command line args" do
     it "creates methods for the args and returns their values" do
-      task = TaskWithArgs.new.print_help_or_call(args: ["--model-name=User", "--model-type=Polymorphic"]).not_nil!
+      task = TaskWithArgs.new.print_help_or_call(args: ["--model-name=User", "--model-type=Polymorphic"]).as(TaskWithArgs)
       task.model_name.should eq "User"
       task.model_type.should eq "Polymorphic"
     end
 
     it "allows the args to be optional" do
-      task = TaskWithArgs.new.print_help_or_call(args: ["--model-name=User"]).not_nil!
+      task = TaskWithArgs.new.print_help_or_call(args: ["--model-name=User"]).as(TaskWithArgs)
       task.model_name.should eq "User"
       task.model_type.should eq nil
     end
 
     it "allows using an arg shortcut" do
-      task = TaskWithArgs.new.print_help_or_call(args: ["-m User"]).not_nil!
+      task = TaskWithArgs.new.print_help_or_call(args: ["-m User"]).as(TaskWithArgs)
       task.model_name.should eq "User"
     end
 
     it "raises an error when an arg is required and not passed" do
-      task = TaskWithRequiredFormatArgs.new.print_help_or_call(args: [""]).not_nil!
+      task = TaskWithRequiredFormatArgs.new.print_help_or_call(args: [""]).as(TaskWithRequiredFormatArgs)
       expect_raises(Exception, /--theme=SOME_VALUE/) do
         task.theme
       end
@@ -80,23 +80,23 @@ describe LuckyTask::Task do
     end
 
     it "sets switch flags that default to false" do
-      task = TaskWithSwitchFlags.new.print_help_or_call(args: [] of String).not_nil!
+      task = TaskWithSwitchFlags.new.print_help_or_call(args: [] of String).as(TaskWithSwitchFlags)
       task.admin?.should eq false
     end
 
     it "sets switch flags from args" do
-      task = TaskWithSwitchFlags.new.print_help_or_call(args: ["-a"]).not_nil!
+      task = TaskWithSwitchFlags.new.print_help_or_call(args: ["-a"]).as(TaskWithSwitchFlags)
       task.admin?.should eq true
     end
 
     it "sets int32 flags that default to 0" do
-      task = TaskWithInt32Flags.new.print_help_or_call(args: [] of String).not_nil!
+      task = TaskWithInt32Flags.new.print_help_or_call(args: [] of String).as(TaskWithInt32Flags)
       task.zero.should eq 0
       task.uno.should eq 1
     end
 
     it "sets int32 flags from args" do
-      task = TaskWithInt32Flags.new.print_help_or_call(args: ["-u 10000", "--zero=1_000"]).not_nil!
+      task = TaskWithInt32Flags.new.print_help_or_call(args: ["-u 10000", "--zero=1_000"]).as(TaskWithInt32Flags)
       task.zero.should eq 1_000
       task.uno.should eq 10_000
       expect_raises(Exception, /"nada" is an invalid value for uno/) do
@@ -105,20 +105,20 @@ describe LuckyTask::Task do
     end
 
     it "sets explicit negative/positive int32 flags from args" do
-      task = TaskWithInt32Flags.new.print_help_or_call(args: ["-u -10_000", "--zero=+1_000"]).not_nil!
+      task = TaskWithInt32Flags.new.print_help_or_call(args: ["-u -10_000", "--zero=+1_000"]).as(TaskWithInt32Flags)
       task.zero.should eq 1_000
       task.uno.should eq -10_000
     end
 
     it "sets float64 flags that default to 0" do
-      task = TaskWithFloat64Flags.new.print_help_or_call(args: [] of String).not_nil!
+      task = TaskWithFloat64Flags.new.print_help_or_call(args: [] of String).as(TaskWithFloat64Flags)
       task.zero.should eq 0.0
       task.uno.should eq 1.0
       task.pi.should eq 3.14
     end
 
     it "sets float64 flags from args" do
-      task = TaskWithFloat64Flags.new.print_help_or_call(args: ["-u 123_456.789", "--zero=1_000"]).not_nil!
+      task = TaskWithFloat64Flags.new.print_help_or_call(args: ["-u 123_456.789", "--zero=1_000"]).as(TaskWithFloat64Flags)
       task.zero.should eq 1_000.0
       task.uno.should eq 123_456.789
       task.pi.should eq 3.14
@@ -128,13 +128,13 @@ describe LuckyTask::Task do
     end
 
     it "sets explicit negative/positive float64 flags from args" do
-      task = TaskWithFloat64Flags.new.print_help_or_call(args: ["-u -100", "--zero=+505.1"]).not_nil!
+      task = TaskWithFloat64Flags.new.print_help_or_call(args: ["-u -100", "--zero=+505.1"]).as(TaskWithFloat64Flags)
       task.zero.should eq 505.1
       task.uno.should eq -100.0
     end
 
     it "allows positional args that do not require a flag name" do
-      task = TaskWithPositionalArgs.new.print_help_or_call(args: ["User", "name:String", "email:String"]).not_nil!
+      task = TaskWithPositionalArgs.new.print_help_or_call(args: ["User", "name:String", "email:String"]).as(TaskWithPositionalArgs)
       task.model.should eq "User"
       task.columns.should eq ["name:String", "email:String"]
     end
diff --git a/spec/lucky_task_spec.cr b/spec/lucky_task_spec.cr
index 1afd23d..d7c41a9 100644
--- a/spec/lucky_task_spec.cr
+++ b/spec/lucky_task_spec.cr
@@ -6,7 +6,7 @@ describe LuckyTask do
       file.gets_to_end
     end
 
-    version = /version\:(.*?)\n/.match(content).not_nil![1].strip
+    version = /version\:(.*?)\n/.match(content).as(Regex::MatchData)[1].strip
     version.should eq LuckyTask::VERSION
   end
 end
diff --git a/src/lucky_task/runner.cr b/src/lucky_task/runner.cr
index 154ff4e..4369afa 100644
--- a/src/lucky_task/runner.cr
+++ b/src/lucky_task/runner.cr
@@ -62,6 +62,6 @@ class LuckyTask::Runner
   end
 
   def self.longest_task_name
-    tasks.map(&.name.size).max
+    tasks.max_of(&.name.size)
   end
 end
diff --git a/src/lucky_task/task.cr b/src/lucky_task/task.cr
index d5fb4fa..8b2363c 100644
--- a/src/lucky_task/task.cr
+++ b/src/lucky_task/task.cr
@@ -5,15 +5,17 @@ abstract class LuckyTask::Task
     property option_parser : OptionParser = OptionParser.new
     property output : IO = STDOUT
 
+    macro finished
     {% if !@type.abstract? %}
       LuckyTask::Runner.tasks << self.new
     {% end %}
+    end
 
-    def name
+    def name : String
       "{{@type.name.gsub(/::/, ".").underscore}}"
     end
 
-    def help_message
+    def help_message : String
       <<-TEXT
       #{summary}
 
@@ -33,7 +35,7 @@ abstract class LuckyTask::Task
       end
     end
 
-    private def wants_help_message?(args)
+    private def wants_help_message?(args) : Bool
       args.any? { |arg| {"--help", "-h", "help"}.includes?(arg) }
     end
   end
@@ -105,7 +107,7 @@ abstract class LuckyTask::Task
       if @{{ arg_name.id }}.nil?
         raise "{{ arg_name.id }} is required, but no value was passed."
       end
-      @{{ arg_name.id }}.not_nil!
+      @{{ arg_name.id }}.as({% if to_end %}Array(String){% else %}String{% end %})
     end
   end
 
@@ -155,7 +157,7 @@ abstract class LuckyTask::Task
             --{{ arg_name.id.stringify.underscore.gsub(/_/, "-").id }}=SOME_VALUE
           ERROR
         end
-        @{{ arg_name.id }}.not_nil!
+        @{{ arg_name.id }}.as(String)
       {% else %}
         @{{ arg_name.id }}
       {% end %}