diff --git a/lib/kramdown-plantuml/options.rb b/lib/kramdown-plantuml/options.rb
index 724fb304..bd9ae51c 100644
--- a/lib/kramdown-plantuml/options.rb
+++ b/lib/kramdown-plantuml/options.rb
@@ -10,7 +10,7 @@ class Options
 
       def initialize(options_hash = {})
         @logger = LogWrapper.init
-        @options = massage(options_hash)
+        @options = massage(options_hash) || {}
         @raise_errors = extract_raise_errors(@options)
         extract_theme_options(@options)
       end
@@ -44,9 +44,9 @@ def extract_plantuml_options(options_hash)
       end
 
       def extract_theme_options(options)
-        return if options.empty? || !options.key?(:theme)
+        return if options.nil? || options.empty? || !options.key?(:theme)
 
-        theme = options[:theme] || {}
+        theme = options[:theme]
 
         unless theme.is_a?(Hash)
           @logger.warn ":theme is not a Hash: #{theme}"
@@ -58,12 +58,10 @@ def extract_theme_options(options)
       end
 
       def extract_raise_errors(options)
-        if options.key?(:raise_errors)
-          raise_errors = options[:raise_errors]
-          return boolean(raise_errors, true)
-        end
+        return true if options.nil? || options.empty? || !options.key?(:raise_errors)
 
-        true
+        raise_errors = options[:raise_errors]
+        boolean(raise_errors, true)
       end
 
       def massage(options_hash)
diff --git a/spec/options_spec.rb b/spec/options_spec.rb
index 30230b83..cc2d5791 100644
--- a/spec/options_spec.rb
+++ b/spec/options_spec.rb
@@ -24,22 +24,50 @@
     its(:to_h) { is_expected.to eq({ }) }
   end
 
+  context 'nil :plantuml' do
+    let(:hash) { { plantuml: nil } }
+    its(:theme_name) { is_expected.to be_nil }
+    its(:theme_directory) { is_expected.to be_nil }
+    its(:raise_errors?) { is_expected.to be true }
+    its(:to_h) { is_expected.to eq({ }) }
+  end
+
   context 'empty :plantuml' do
     let(:hash) { { plantuml: { } } }
     its(:to_h) { is_expected.to eq({ }) }
   end
 
+  context 'nil :theme' do
+    let(:hash) { { plantuml: { theme: nil } } }
+    its(:to_h) { is_expected.to eq({ theme: nil }) }
+  end
+
   context 'empty :theme' do
     let(:hash) { { plantuml: { theme: {  } } } }
     its(:to_h) { is_expected.to eq({ theme: { } }) }
   end
 
+  context 'with nil :name' do
+    let(:hash) { { plantuml: { theme: { name: nil } } } }
+    its(:to_h) { is_expected.to eq({ theme: { name: nil } }) }
+  end
+
   context 'with :theme :name' do
     let(:hash) { { plantuml: { theme: { name: 'custom' } } } }
     its(:to_h) { is_expected.to eq({ theme: { name: 'custom' } }) }
   end
 
-  context 'invalid :raise_errors' do
+  context 'with nil :directory' do
+    let(:hash) { { plantuml: { theme: { name: 'custom', directory: nil } } } }
+    its(:to_h) { is_expected.to eq({ theme: { name: 'custom', directory: nil } }) }
+  end
+
+  context 'with nil :raise_errors' do
+    let(:hash) { { plantuml: { theme: { }, raise_errors: nil } } }
+    its(:raise_errors?) { is_expected.to be true }
+  end
+
+  context 'with invalid :raise_errors' do
     let(:hash) { { plantuml: { theme: { }, raise_errors: 'xyz' } } }
     its(:raise_errors?) { is_expected.to be true }
   end