diff --git a/LICENCE.md b/LICENCE.md
index f255ec0cb062..cae2c6930837 100644
--- a/LICENCE.md
+++ b/LICENCE.md
@@ -1,6 +1,6 @@
 # TruffleRuby Licence
 
-TruffleRuby is copyright (c) 2013-2022 Oracle and/or its affiliates, and is made
+TruffleRuby is copyright (c) 2013-2023 Oracle and/or its affiliates, and is made
 available to you under the terms of any one of the following three licenses:
 
 * Eclipse Public License version 2.0, or
diff --git a/README.md b/README.md
index 2e33b668becd..d85caee71bed 100644
--- a/README.md
+++ b/README.md
@@ -179,7 +179,7 @@ For known vulnerabilities in Ruby, please refer to the [known-cves](doc/user/kno
 
 ## Licence
 
-TruffleRuby is copyright (c) 2013-2022 Oracle and/or its affiliates, and is made
+TruffleRuby is copyright (c) 2013-2023 Oracle and/or its affiliates, and is made
 available to you under the terms of any one of the following three licenses:
 
 * Eclipse Public License version 2.0, or
diff --git a/doc/legal/legal.md b/doc/legal/legal.md
index 2548630c8a61..29204d90d5e8 100644
--- a/doc/legal/legal.md
+++ b/doc/legal/legal.md
@@ -6,7 +6,7 @@ use TruffleRuby.
 
 ## TruffleRuby
 
-TruffleRuby is copyright (c) 2013-2022 Oracle and/or its
+TruffleRuby is copyright (c) 2013-2023 Oracle and/or its
 affiliates, and is made available to you under the terms of any one of the
 following three licenses:
 
diff --git a/tool/update_copyright.rb b/tool/update_copyright.rb
index 51fd042e64b9..38745680310b 100644
--- a/tool/update_copyright.rb
+++ b/tool/update_copyright.rb
@@ -40,9 +40,10 @@
   '.h' => JAVA_COPYRIGHT,
 }
 
-EXTENSIONS = %w[.java .rb .c .h]
+EXTENSIONS = %w[.java .rb .c .h .md]
 
-COPYRIGHT = /Copyright \(c\) (?<year1>\d{4})(?:, (?<year2>\d{4}))* Oracle\b/
+COPYRIGHT = /(?<copyright>Copyright) \(c\) (?<year1>\d{4})(?:(?<sep>, )(?<year2>\d{4}))? Oracle\b/
+COPYRIGHT_MARKDOWN = /(?<copyright>copyright) \(c\) (?<year1>\d{4})(?:(?<sep>-)(?<year2>\d{4}))? Oracle\b/
 
 OTHER_COPYRIGHTS = [
   /Copyright \(c\) \d{4}(?:-\d{4})?,? Evan Phoenix/,
@@ -66,6 +67,9 @@
   test/truffle
   tool/generate
   spec/truffle
+  LICENCE.md
+  README.md
+  doc/legal/legal.md
 ] + [__FILE__]
 
 excludes = %w[
@@ -115,24 +119,29 @@
 }
 
 paths.each do |file|
-  header = File.read(file, 400)
+  ext = File.extname(file)
+  md = ext == '.md'
+  header = File.read(file, *(400 unless md))
 
-  unless COPYRIGHT =~ header
+  copyright_regexp = md ? COPYRIGHT_MARKDOWN : COPYRIGHT
+
+  unless copyright_regexp =~ header
+    next if md
     if OTHER_COPYRIGHTS.none? { |copyright| copyright =~ header }
       puts "Adding copyright in #{file}"
-      File.write(file, NEW_COPYRIGHT[File.extname(file)]+File.read(file))
+      File.write(file, NEW_COPYRIGHT[ext]+File.read(file))
     end
     next
   end
 
-  year1, year2 = $~[:year1], $~[:year2]
+  copyright, year1, sep, year2 = $~[:copyright], $~[:year1], $~[:sep], $~[:year2]
   year1 = Integer(year1)
   year2 = Integer(year2 || year1)
 
   if year > year2
     contents = File.read(file)
-    years = "#{year1}, #{year}"
-    contents.sub!(COPYRIGHT, "Copyright (c) #{years} Oracle")
+    years = "#{year1}#{sep}#{year}"
+    contents.sub!(copyright_regexp, "#{copyright} (c) #{years} Oracle")
     File.write(file, contents)
 
     puts "Updated year in #{file}"