diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 366a053..a320273 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,6 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
-          - 2.5
           - 2.6
           - 2.7
           - 3.0
diff --git a/.standard.yml b/.standard.yml
index 33ea7ae..3af9da5 100644
--- a/.standard.yml
+++ b/.standard.yml
@@ -1 +1 @@
-ruby_version: 2.5
+ruby_version: 2.6
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4a920d0..4a41647 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 ## HEAD (unreleased)
 
-- Minimum Ruby version is now Ruby 2.5
+- Minimum Ruby version is now Ruby 2.6
 - Add `bigdecimal` as a dependency.
 
 ## 0.2.7
diff --git a/get_process_mem.gemspec b/get_process_mem.gemspec
index 5d980db..e5b97b0 100644
--- a/get_process_mem.gemspec
+++ b/get_process_mem.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |gem|
   gem.executables = gem.files.grep(%r{^bin/}).map { |f| File.basename(f) }
   gem.require_paths = ["lib"]
 
-  gem.required_ruby_version = ">= 2.5"
+  gem.required_ruby_version = ">= 2.6"
 
   gem.add_dependency "ffi", "~> 1.0"
   gem.add_dependency "bigdecimal", ">= 2.0"