diff --git a/lib/msf/core/opt_enum.rb b/lib/msf/core/opt_enum.rb
index 344b45b3a5f6..214cfd324506 100644
--- a/lib/msf/core/opt_enum.rb
+++ b/lib/msf/core/opt_enum.rb
@@ -20,13 +20,22 @@ def initialize(in_name, attrs = [],
     def valid?(value = self.value, check_empty: true)
       return false if check_empty && empty_required_value?(value)
       return true if value.nil? && !required?
+      return false if value.nil?
 
-      !value.nil? && enums.include?(value.to_s)
+      if case_sensitive?
+        enums.include?(value.to_s)
+      else
+        enums.map(&:downcase).include?(value.to_s.downcase)
+      end
     end
 
     def normalize(value = self.value)
       if valid?(value) && !value.nil?
-        value.to_s
+        if case_sensitive?
+          value.to_s
+        else
+          enums.find { |e| e.casecmp? value }
+        end
       else
         nil
       end
@@ -44,6 +53,10 @@ def desc
 
     protected
 
+    def case_sensitive?
+      enums.map(&:downcase).uniq.length != enums.uniq.length
+    end
+
     attr_accessor :desc_string # :nodoc:
   end
 end
diff --git a/spec/lib/msf/core/opt_enum_spec.rb b/spec/lib/msf/core/opt_enum_spec.rb
index fac6e72fd898..de0d02cbbd15 100644
--- a/spec/lib/msf/core/opt_enum_spec.rb
+++ b/spec/lib/msf/core/opt_enum_spec.rb
@@ -17,6 +17,10 @@
       expect(required_optenum.valid?('Bar')).to eq true
     end
 
+    it 'should return true for a value in the list with alternative casing' do
+      expect(required_optenum.valid?('bar')).to eq true
+    end
+
     it 'should return false for a nil value' do
       expect(required_optenum.valid?(nil)).to eq false
     end
@@ -31,6 +35,10 @@
       expect(not_required_optenum.valid?('Bar')).to eq true
     end
 
+    it 'should return true for a value in the list with alternative casing' do
+      expect(not_required_optenum.valid?('bar')).to eq true
+    end
+
     it 'should return false for a value not in the list' do
       expect(not_required_optenum.valid?('Snap')).to eq false
     end
@@ -45,6 +53,10 @@
       expect(required_optenum.normalize('Bar')).to eq 'Bar'
     end
 
+    it 'should return the value string for a value with alternative casing' do
+      expect(required_optenum.normalize('bar')).to eq 'Bar'
+    end
+
     it 'should return nil for a value not in the list' do
       expect(required_optenum.normalize('Snap')).to eq nil
     end
@@ -59,6 +71,10 @@
       expect(not_required_optenum.normalize('Bar')).to eq 'Bar'
     end
 
+    it 'should return the value string for a value with alternative casing' do
+      expect(not_required_optenum.normalize('bar')).to eq 'Bar'
+    end
+
     it 'should return nil for a value not in the list' do
       expect(not_required_optenum.normalize('Snap')).to eq nil
     end