diff --git a/.hoerc b/.hoerc
index 0d0aae2..55c87d2 100644
--- a/.hoerc
+++ b/.hoerc
@@ -1,8 +1,8 @@
 ---
 exclude: !ruby/regexp '/
   \.(?:
-    tmp
-    | swp
+    tmp |
+    swp
   )$
   |
   \.(?:
@@ -18,7 +18,8 @@ exclude: !ruby/regexp '/
   [gG]emfile(?:\.lock)?
   |
   (?:
-    support
+    support |
+    research
   )\/
   |
   \b(?i:TAGS)$
diff --git a/lib/mime/type.rb b/lib/mime/type.rb
index 23036d5..259af18 100644
--- a/lib/mime/type.rb
+++ b/lib/mime/type.rb
@@ -187,8 +187,8 @@ def like?(other)
 
   # Compares the +other+ MIME::Type against the exact content type or the
   # simplified type (the simplified type will be used if comparing against
-  # something that can be treated as a String with #to_s). In comparisons,
-  # this is done against the lowercase version of the MIME::Type.
+  # something that can be treated as a String with #to_s). In comparisons, this
+  # is done against the lowercase version of the MIME::Type.
   #
   # Note that this implementation of #<=> is deprecated and will be changed
   # in the next major version to be the same as #priority_compare.
diff --git a/lib/mime/types.rb b/lib/mime/types.rb
index a632a0b..ab891f0 100644
--- a/lib/mime/types.rb
+++ b/lib/mime/types.rb
@@ -152,9 +152,9 @@ def [](type_id, complete: false, registered: false)
   #     => [application/xml, image/gif, text/xml]
   def type_for(filename)
     Array(filename).flat_map { |fn|
-      @extension_index[fn.chomp.downcase[/\.?([^.]*?)\z/, 1]]
+      @extension_index[fn.chomp.downcase[/\.?([^.]*?)\z/m, 1]]
     }.compact.inject(Set.new, :+).sort { |a, b|
-      by_ext = a.extension_priority(*extensions) <=> b.extension_priority(*extensions)
+      by_ext = a.extension_priority(*a.extensions) <=> b.extension_priority(*b.extensions)
 
       if by_ext.zero?
         a.priority_compare(b)