diff --git a/Changelog.md b/Changelog.md
index 278baf4a..7cdfab85 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,3 +1,11 @@
+# v0.6.3 2022-01-16
+
+[#290](https://github.com/mbj/unparser/pull/290)
+
+* Depend on parser-3.1.0.
+* This is not yet Ruby 3.1 syntax support, only
+  supporting the existing feature set on an updated `parser` gem.
+
 # v0.6.2 2021-11-09
 
 [#281](https://github.com/mbj/unparser/pull/268)
diff --git a/Gemfile b/Gemfile
index 1419592e..08a192d1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,6 +4,8 @@ source 'https://rubygems.org'
 
 gemspec
 
+gem 'mutant', git: 'https://github.com/mbj/mutant', ref: '2fbc9dc7f8a8d363bc9fad6a32b0a6c9d1032743'
+
 source 'https://oss:Px2ENN7S91OmWaD5G7MIQJi1dmtmYrEh@gem.mutant.dev' do
   gem 'mutant-license'
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index 284438b0..ef3d1f9f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,9 +1,21 @@
+GIT
+  remote: https://github.com/mbj/mutant
+  revision: 2fbc9dc7f8a8d363bc9fad6a32b0a6c9d1032743
+  ref: 2fbc9dc7f8a8d363bc9fad6a32b0a6c9d1032743
+  specs:
+    mutant (0.11.2)
+      diff-lcs (~> 1.3)
+      parser (~> 3.1.0)
+      regexp_parser (~> 2.0, >= 2.0.3)
+      sorbet-runtime (~> 0.5.0)
+      unparser (~> 0.6.2)
+
 PATH
   remote: .
   specs:
-    unparser (0.6.2)
+    unparser (0.6.3)
       diff-lcs (~> 1.3)
-      parser (>= 3.0.0)
+      parser (>= 3.1.0)
 
 GEM
   remote: https://oss:Px2ENN7S91OmWaD5G7MIQJi1dmtmYrEh@gem.mutant.dev/
@@ -14,21 +26,15 @@ GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.2)
-    diff-lcs (1.4.4)
-    mutant (0.11.1)
-      diff-lcs (~> 1.3)
-      parser (~> 3.0.0)
-      regexp_parser (~> 2.0, >= 2.0.3)
-      sorbet-runtime (~> 0.5.0)
-      unparser (~> 0.6.0)
-    mutant-rspec (0.11.1)
-      mutant (= 0.11.1)
+    diff-lcs (1.5.0)
+    mutant-rspec (0.11.2)
+      mutant (= 0.11.2)
       rspec-core (>= 3.8.0, < 4.0.0)
     parallel (1.21.0)
-    parser (3.0.2.0)
+    parser (3.1.0.0)
       ast (~> 2.4.1)
-    rainbow (3.0.0)
-    regexp_parser (2.1.1)
+    rainbow (3.1.1)
+    regexp_parser (2.2.0)
     rexml (3.2.5)
     rspec (3.10.0)
       rspec-core (~> 3.10.0)
@@ -36,7 +42,7 @@ GEM
       rspec-mocks (~> 3.10.0)
     rspec-core (3.10.1)
       rspec-support (~> 3.10.0)
-    rspec-expectations (3.10.1)
+    rspec-expectations (3.10.2)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.10.0)
     rspec-its (1.3.0)
@@ -45,29 +51,29 @@ GEM
     rspec-mocks (3.10.2)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.10.0)
-    rspec-support (3.10.2)
-    rubocop (1.23.0)
+    rspec-support (3.10.3)
+    rubocop (1.24.1)
       parallel (~> 1.10)
       parser (>= 3.0.0.0)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.8, < 3.0)
       rexml
-      rubocop-ast (>= 1.12.0, < 2.0)
+      rubocop-ast (>= 1.15.1, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.13.0)
+    rubocop-ast (1.15.1)
       parser (>= 3.0.1.1)
     rubocop-packaging (0.5.1)
       rubocop (>= 0.89, < 2.0)
     ruby-progressbar (1.11.0)
-    sorbet-runtime (0.5.9307)
+    sorbet-runtime (0.5.9531)
     unicode-display_width (2.1.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  mutant (~> 0.11.1)
+  mutant!
   mutant-license!
   mutant-rspec (~> 0.11.1)
   rspec (~> 3.9)
diff --git a/unparser.gemspec b/unparser.gemspec
index 74f45acc..431b27da 100644
--- a/unparser.gemspec
+++ b/unparser.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |gem|
   gem.name        = 'unparser'
-  gem.version     = '0.6.2'
+  gem.version     = '0.6.3'
 
   gem.authors     = ['Markus Schirp']
   gem.email       = 'mbj@schirp-dso.com'
@@ -24,7 +24,7 @@ Gem::Specification.new do |gem|
   gem.required_ruby_version = '>= 2.6'
 
   gem.add_dependency('diff-lcs', '~> 1.3')
-  gem.add_dependency('parser',   '>= 3.0.0')
+  gem.add_dependency('parser',   '>= 3.1.0')
 
   gem.add_development_dependency('mutant',            '~> 0.11.1')
   gem.add_development_dependency('mutant-rspec',      '~> 0.11.1')