diff --git a/CHANGELOG.md b/CHANGELOG.md
index 92afe19..7b82906 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Irbtools Changelog
 
+## 4.0.9 (unreleased)
+
+* Fix loading command `Base` class and require IRB 1.12 to make sure it is available
+
 ## 4.0.8
 
 * Require IRB 1.11
diff --git a/README.md b/README.md
index 82164a0..64a6106 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 ## Irbtools 4 for Current IRB
 
-The current version of Irbtools requires [IRB 1.11+](https://github.com/ruby/irb) ([which Ruby version bundles which IRB?](https://stdgems.org/irb/)). Please use Irbtools 3 for earlier versions of IRB.
+The current version of Irbtools requires [IRB 1.12+](https://github.com/ruby/irb) ([which Ruby version bundles which IRB?](https://stdgems.org/irb/)). Please use Irbtools 3 for earlier versions of IRB.
 
 ## Description
 
diff --git a/irbtools.gemspec b/irbtools.gemspec
index a13414e..9039bf2 100644
--- a/irbtools.gemspec
+++ b/irbtools.gemspec
@@ -20,7 +20,7 @@ Gem::Specification.new do |s|
   # Dependencies
 
   # Core Functionality
-  s.add_dependency %q<irb>,           ">= 1.11", "< 1.13"
+  s.add_dependency %q<irb>,           "~> 1.12.0"
   s.add_dependency %q<every_day_irb>, "~> 2.2"
   s.add_dependency %q<fancy_irb>,     "~> 2.1"
   s.add_dependency %q<wirb>,          "~> 2.0", ">= 2.2.1"
diff --git a/lib/irbtools/commands/code.rb b/lib/irbtools/commands/code.rb
index e68590f..29dc5ff 100644
--- a/lib/irbtools/commands/code.rb
+++ b/lib/irbtools/commands/code.rb
@@ -1,4 +1,4 @@
-require "irb"
+require "irb/command/base"
 
 module IRB
   module Command
diff --git a/lib/irbtools/commands/howtocall.rb b/lib/irbtools/commands/howtocall.rb
index 13bcd96..24f4fd2 100644
--- a/lib/irbtools/commands/howtocall.rb
+++ b/lib/irbtools/commands/howtocall.rb
@@ -1,4 +1,4 @@
-require "irb"
+require "irb/command/base"
 
 module IRB
   module Command
diff --git a/lib/irbtools/commands/look.rb b/lib/irbtools/commands/look.rb
index 7887c48..e16ae34 100644
--- a/lib/irbtools/commands/look.rb
+++ b/lib/irbtools/commands/look.rb
@@ -1,4 +1,4 @@
-require "irb"
+require "irb/command/base"
 
 module IRB
   module Command
diff --git a/lib/irbtools/commands/shadow.rb b/lib/irbtools/commands/shadow.rb
index 9da70f7..3a28b97 100644
--- a/lib/irbtools/commands/shadow.rb
+++ b/lib/irbtools/commands/shadow.rb
@@ -1,4 +1,4 @@
-require "irb"
+require "irb/command/base"
 
 module IRB
   module Command
diff --git a/lib/irbtools/commands/sys.rb b/lib/irbtools/commands/sys.rb
index 877467f..d06fcaa 100644
--- a/lib/irbtools/commands/sys.rb
+++ b/lib/irbtools/commands/sys.rb
@@ -1,4 +1,4 @@
-require "irb"
+require "irb/command/base"
 
 module IRB
   module Command