diff --git a/CHANGELOG.md b/CHANGELOG.md
index f1350f4..100a5a7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ _No breaking changes!_
 **Project enhancements:**
 
 - Fixed a bug that overwrote existing self.extended method definitions. [[#324]](https://github.com/panorama-ed/memo_wise/pull/314)
+- Fixed a bug that overwrote existing self.inherited method definitions. [[#325]](https://github.com/panorama-ed/memo_wise/pull/315)
 
 ## [v1.8.0](https://github.com/panorama-ed/memo_wise/compare/v1.7.0...v1.8.0) - 2023-10-25
 
diff --git a/lib/memo_wise.rb b/lib/memo_wise.rb
index 6c9c67b..f88ff80 100644
--- a/lib/memo_wise.rb
+++ b/lib/memo_wise.rb
@@ -86,6 +86,14 @@ def extended(base)
   end
   private_constant(:CreateMemoWiseStateOnExtended)
 
+  module CreateMemoWiseStateOnInherited
+    def inherited(subclass)
+      super
+      MemoWise::InternalAPI.create_memo_wise_state!(subclass)
+    end
+  end
+  private_constant(:CreateMemoWiseStateOnInherited)
+
   # @private
   #
   # Private setup method, called automatically by `prepend MemoWise` in a class.
@@ -165,12 +173,15 @@ def memo_wise(method_name_or_hash)
 
         # This ensures that a memoized method defined on a parent class can
         # still be used in a child class.
-        klass.module_eval <<~HEREDOC, __FILE__, __LINE__ + 1
-          def inherited(subclass)
-            super
-            MemoWise::InternalAPI.create_memo_wise_state!(subclass)
+        if klass.is_a?(Class)
+          if klass.singleton_class?
+            klass.prepend(CreateMemoWiseStateOnInherited)
+          else
+            klass.singleton_class.prepend(CreateMemoWiseStateOnInherited)
           end
-        HEREDOC
+        else
+          klass.prepend(CreateMemoWiseStateOnInherited)
+        end
 
         raise ArgumentError, "#{method_name.inspect} must be a Symbol" unless method_name.is_a?(Symbol)
 
diff --git a/spec/memo_wise_spec.rb b/spec/memo_wise_spec.rb
index 7278ac0..b72321d 100644
--- a/spec/memo_wise_spec.rb
+++ b/spec/memo_wise_spec.rb
@@ -842,5 +842,85 @@ def no_args; end
         expect(instance.instance_variable_get(:@extended_called)).to be(true)
       end
     end
+
+    context "with target defined self.inherited" do
+      context "when target is class" do
+        let(:klass) do
+          Class.new do
+            prepend MemoWise
+
+            def self.inherited(subclass)
+              subclass.instance_variable_set(:@inherited_called, true)
+            end
+
+            def no_args; end
+            memo_wise :no_args
+          end
+        end
+
+        it "calls defined self.inherited" do
+          expect(Class.new(klass).instance_variable_get(:@inherited_called)).to be(true)
+        end
+
+        it "doesn't define #inherited" do
+          expect(klass).to be_respond_to(:inherited)
+          expect(klass.new).to_not be_respond_to(:inherited)
+        end
+      end
+
+      context "when target is singleton class" do
+        let(:klass) do
+          Class.new do
+            class << self
+              prepend MemoWise
+
+              def inherited(subclass)
+                subclass.instance_variable_set(:@inherited_called, true)
+              end
+
+              def no_args; end
+              memo_wise :no_args
+            end
+          end
+        end
+
+        it "calls defined self.inherited" do
+          expect(Class.new(klass).instance_variable_get(:@inherited_called)).to be(true)
+        end
+
+        it "doesn't define #inherited" do
+          expect(klass).to be_respond_to(:inherited)
+          expect(klass.new).to_not be_respond_to(:inherited)
+        end
+      end
+
+      context "when target is module" do
+        let(:klass) do
+          mod = Module.new do
+            prepend MemoWise
+
+            def inherited(subclass)
+              subclass.instance_variable_set(:@inherited_called, true)
+            end
+
+            def no_args; end
+            memo_wise :no_args
+          end
+
+          klass = Class.new
+          klass.extend(mod)
+          klass
+        end
+
+        it "calls defined self.inherited" do
+          expect(Class.new(klass).instance_variable_get(:@inherited_called)).to be(true)
+        end
+
+        it "doesn't define #inherited" do
+          expect(klass).to be_respond_to(:inherited)
+          expect(klass.new).to_not be_respond_to(:inherited)
+        end
+      end
+    end
   end
 end