diff --git a/lib/jekyll/excerpt.rb b/lib/jekyll/excerpt.rb
index dee4613f..c7048e6e 100644
--- a/lib/jekyll/excerpt.rb
+++ b/lib/jekyll/excerpt.rb
@@ -155,7 +155,7 @@ module Jekyll
       tag_names.flatten!
       tag_names.reverse_each do |tag_name|
         next unless liquid_block?(tag_name)
-        next if head =~ endtag_regex_stash(tag_name)
+        next if endtag_regex_stash(tag_name).match?(head)
 
         modified = true
         head << "\n{% end#{tag_name} %}"
diff --git a/lib/jekyll/filters.rb b/lib/jekyll/filters.rb
index cec65ba3..0353e857 100644
--- a/lib/jekyll/filters.rb
+++ b/lib/jekyll/filters.rb
@@ -368,6 +368,7 @@ module Jekyll
       end
     end
 
+    # rubocop:disable Performance/RegexpMatch
     # return numeric values as numbers for proper sorting
     def parse_sort_input(property)
       number_like = %r!\A\s*-?(?:\d+\.?\d*|\.\d+)\s*\Z!
@@ -375,6 +376,7 @@ module Jekyll
 
       property
     end
+    # rubocop:enable Performance/RegexpMatch
 
     def as_liquid(item)
       case item
diff --git a/lib/jekyll/readers/post_reader.rb b/lib/jekyll/readers/post_reader.rb
index bdbe6f5c..17b12321 100644
--- a/lib/jekyll/readers/post_reader.rb
+++ b/lib/jekyll/readers/post_reader.rb
@@ -50,7 +50,7 @@ module Jekyll
     # Returns klass type of content files
     def read_content(dir, magic_dir, matcher)
       @site.reader.get_entries(dir, magic_dir).map do |entry|
-        next unless entry =~ matcher
+        next unless matcher.match?(entry)
 
         path = @site.in_source_dir(File.join(dir, magic_dir, entry))
         Document.new(path,