diff --git a/Rakefile b/Rakefile
index 7fb47ba..f1b3abb 100644
--- a/Rakefile
+++ b/Rakefile
@@ -3,4 +3,11 @@ require "minitest/test_task"
 
 Minitest::TestTask.create(:test)
 
+namespace :test do
+  desc "Run tests on Ruby file changes"
+  task :watch do
+    sh "fd .*.rb | entr -d rake test"
+  end
+end
+
 task :default => :test
diff --git a/lib/minitest/thesis.rb b/lib/minitest/thesis.rb
index 7560336..ae42463 100644
--- a/lib/minitest/thesis.rb
+++ b/lib/minitest/thesis.rb
@@ -46,7 +46,7 @@ module Minitest
 
       prev_failure = database[name]
 
-      unless prev_failure.nil?
+      if prev_failure
         choices = prev_failure.unpack("Q>*")
         state.test_function(TestCase.for_choices(choices))
       end
@@ -101,13 +101,10 @@ module Minitest
 
       # Return True with probability `p`.
       def weighted(p)
-        if p.zero? || p.negative?
-          result = forced_choice(0)
-        elsif p >= 1
-          result = forced_choice(1)
-        else
-          result = make_choice(1) { (@random.rand <= p) ? 1 : 0 }
-        end
+        result = if    p <= 0 then forced_choice(0)
+                 elsif p >= 1 then forced_choice(1)
+                 else              make_choice(1) { (@random.rand <= p) ? 1 : 0 }
+                 end
 
         puts "weighted(#{p}): #{result}" if should_print?
 
@@ -118,7 +115,6 @@ module Minitest
       # choice() had returned `n`. You almost never need this, but sometimes it
       # can be a useful hint to the shrinker.
       def forced_choice(n)
-
         raise RangeError.new("Invalid choice #{n}") if n.bit_length > 64 || n.negative?
         raise Frozen unless @status.nil?