diff --git a/lib/mime/type.rb b/lib/mime/type.rb
index ec4fb67..0b3f747 100644
--- a/lib/mime/type.rb
+++ b/lib/mime/type.rb
@@ -190,7 +190,7 @@ def <=>(other)
   # consumers of mime-types. For the next major version of MIME::Types, this
   # method will become #<=> and #priority_compare will be removed.
   def priority_compare(other)
-    if (cmp = __sort_priority <=> other.__sort_priority).zero?
+    if (cmp = __sort_priority <=> other.__sort_priority) == 0
       simplified <=> other.simplified
     else
       cmp
@@ -689,15 +689,15 @@ def clear_sort_priority
   # 16, to a minimum of 0.
   def update_sort_priority
     extension_count = @extensions.length
-    obsolete = instance_variable_defined?(:@obsolete) && @obsolete ? 1 << 7 : 0
-    provisional = instance_variable_defined?(:@provisional) && @provisional ? 1 << 6 : 0
-    registered = instance_variable_defined?(:@registered) && @registered ? 0 : 1 << 5
+    obsolete = (instance_variable_defined?(:@obsolete) && @obsolete) ? 1 << 7 : 0
+    provisional = (instance_variable_defined?(:@provisional) && @provisional) ? 1 << 6 : 0
+    registered = (instance_variable_defined?(:@registered) && @registered) ? 0 : 1 << 5
     complete = extension_count.nonzero? ? 0 : 1 << 4
     extension_count = [0, 16 - extension_count].max
 
     @__sort_priority = obsolete | registered | provisional | complete | extension_count
-    @__priority_penalty = (instance_variable_defined?(:@obsolete) && @obsolete ? 3 : 0) +
-      (instance_variable_defined?(:@registered) && @registered ? 0 : 2)
+    @__priority_penalty = ((instance_variable_defined?(:@obsolete) && @obsolete) ? 3 : 0) +
+      ((instance_variable_defined?(:@registered) && @registered) ? 0 : 2)
   end
 
   def __priority_penalty
diff --git a/lib/mime/types.rb b/lib/mime/types.rb
index b8e1377..a632a0b 100644
--- a/lib/mime/types.rb
+++ b/lib/mime/types.rb
@@ -151,10 +151,8 @@ def [](type_id, complete: false, registered: false)
   #   puts MIME::Types.type_for(%w(citydesk.xml citydesk.gif))
   #     => [application/xml, image/gif, text/xml]
   def type_for(filename)
-    extensions = Array(filename).map { |fn| fn.chomp.downcase[/\.?([^.]*?)$/, 1] }
-
-    extensions.flat_map { |ext|
-      @extension_index[ext]
+    Array(filename).flat_map { |fn|
+      @extension_index[fn.chomp.downcase[/\.?([^.]*?)\z/, 1]]
     }.compact.inject(Set.new, :+).sort { |a, b|
       by_ext = a.extension_priority(*extensions) <=> b.extension_priority(*extensions)
 
diff --git a/lib/mime/types/deprecations.rb b/lib/mime/types/deprecations.rb
index 05645a9..c2810ed 100644
--- a/lib/mime/types/deprecations.rb
+++ b/lib/mime/types/deprecations.rb
@@ -32,7 +32,7 @@ def self.deprecated(klass, sym, message = nil, &block) # :nodoc:
           " #{message}"
         end
 
-      MIME::Types.logger.warn <<-WARNING.chomp.strip
+      MIME::Types.logger.debug <<-WARNING.chomp.strip
         #{caller(2..2).first}: #{klass}#{level}#{sym}#{pre_message} is deprecated#{message}.
       WARNING
 
diff --git a/test/test_mime_type.rb b/test/test_mime_type.rb
index 43a91d3..0a0666a 100644
--- a/test/test_mime_type.rb
+++ b/test/test_mime_type.rb
@@ -265,27 +265,27 @@ def mime_type(content_type)
     end
 
     it "is true for an equivalent MIME::Type" do
-      assert text_plain.eql?(mime_type("text/Plain"))
+      assert text_plain.eql?(mime_type("content-type" => "text/Plain"))
     end
 
     it "is true for an equivalent subclass of MIME::Type" do
       subclass = Class.new(MIME::Type)
-      assert text_plain.eql?(subclass.new("text/plain"))
+      assert text_plain.eql?(subclass.new("content-type" => "text/plain"))
     end
   end
 
   describe "#hash" do
     it "is the same between #eql? MIME::Type instances" do
-      assert_equal text_plain.hash, mime_type("text/plain").hash
+      assert_equal text_plain.hash, mime_type("content-type" => "text/plain").hash
     end
 
     it "is the same between #eql? MIME::Type instances of different classes" do
       subclass = Class.new(MIME::Type)
-      assert_equal text_plain.hash, subclass.new("text/plain").hash
+      assert_equal text_plain.hash, subclass.new("content-type" => "text/plain").hash
     end
 
     it "uses the #simplified value" do
-      assert_equal text_plain.hash, mime_type("text/Plain").hash
+      assert_equal text_plain.hash, mime_type("content-type" => "text/Plain").hash
     end
   end
 
@@ -322,11 +322,11 @@ def mime_type(content_type)
 
   describe "#priority_compare" do
     def priority(type)
-      "#{type} (#{("%08b" % type.__sort_priority).split(//).join(" ")})"
+      "#{type} (#{("%08b" % type.__sort_priority).chars.join(" ")})"
     end
 
     def assert_priority_less(left, right)
-      assert_equal -1, left.priority_compare(right), "#{priority(left)} is not less than #{priority(right)}"
+      assert_equal(-1, left.priority_compare(right), "#{priority(left)} is not less than #{priority(right)}")
     end
 
     def assert_priority_same(left, right)
@@ -367,7 +367,6 @@ def assert_priority(left, middle, right)
       assert_priority text_1, text_1p, text_1b
     end
 
-
     it "sorts (3) based on the registration state" do
       text_1.registered = text_1p.registered = true
       text_1b = mime_type(text_1) { |t| t.registered = false }
@@ -382,7 +381,6 @@ def assert_priority(left, middle, right)
       assert_priority text_1, text_1p, text_1b
     end
 
-
     it "sorts (5) based on the use-instead value" do
       text_1.obsolete = text_1p.obsolete = true
       text_1.use_instead = text_1p.use_instead = "abc/xyz"
@@ -401,7 +399,6 @@ def assert_priority(left, middle, right)
 
       assert_priority_less text_1, text_2
     end
-
   end
 
   describe "#raw_media_type" do
diff --git a/test/test_mime_types_class.rb b/test/test_mime_types_class.rb
index b42d643..66122f3 100644
--- a/test/test_mime_types_class.rb
+++ b/test/test_mime_types_class.rb
@@ -86,7 +86,7 @@ def setup
       assert_equal %w[image/jpeg], MIME::Types.of(["foo.jpeg", "bar.jpeg"])
     end
 
-    it "finds multiple extensions" do
+    it "finds multiple extensions ordered by the filename list" do
       assert_equal %w[text/plain image/jpeg], MIME::Types.type_for(%w[foo.txt foo.jpeg])
     end