diff --git a/lib/nanaimo/writer.rb b/lib/nanaimo/writer.rb
index 9b21c23..256e8ed 100644
--- a/lib/nanaimo/writer.rb
+++ b/lib/nanaimo/writer.rb
@@ -90,7 +90,7 @@ def write_object(object)
       output
     end
 
-    QUOTED_STRING_REGEXP = %r{\A\z|[^\w\./]|\A___}
+    QUOTED_STRING_REGEXP = %r{\A\z|[^\w\.\$/]|\A___}
     private_constant :QUOTED_STRING_REGEXP
 
     def write_string_quoted_if_necessary(object)
diff --git a/spec/nanaimo/writer_spec.rb b/spec/nanaimo/writer_spec.rb
index d6a0a64..8734e09 100644
--- a/spec/nanaimo/writer_spec.rb
+++ b/spec/nanaimo/writer_spec.rb
@@ -80,6 +80,14 @@ def to_s
           expect(subject).to eq("#{utf8}Value /*A whimsical value*/\n")
         end
       end
+
+      describe 'string with dollar sign' do
+        let(:root_object) { %($ABC) }
+
+        it 'writes without quotes' do
+          expect(subject).to eq(%(#{utf8}$ABC\n))
+        end
+      end
     end
 
     describe QuotedString do