diff --git a/lib/csv/fields_converter.rb b/lib/csv/fields_converter.rb
index a751c9ea1d495b..178ffb37bc8da7 100644
--- a/lib/csv/fields_converter.rb
+++ b/lib/csv/fields_converter.rb
@@ -50,7 +50,7 @@ def convert(fields, headers, lineno)
       fields.collect.with_index do |field, index|
         if field.nil?
           field = @nil_value
-        elsif field.empty?
+        elsif field.is_a?(String) and field.empty?
           field = @empty_value unless @empty_value_is_empty_string
         end
         @converters.each do |converter|
diff --git a/test/csv/write/test_converters.rb b/test/csv/write/test_converters.rb
index a93b1040ac60da..0e0080b4c5cb73 100644
--- a/test/csv/write/test_converters.rb
+++ b/test/csv/write/test_converters.rb
@@ -20,14 +20,14 @@ def test_multiple
   end
 
   def test_nil_value
-    assert_equal(%Q[a,NaN,c\n],
-                 generate_line(["a", nil, "c"],
+    assert_equal(%Q[a,NaN,29\n],
+                 generate_line(["a", nil, 29],
                                write_nil_value: "NaN"))
   end
 
   def test_empty_value
-    assert_equal(%Q[a,,c\n],
-                 generate_line(["a", "", "c"],
+    assert_equal(%Q[a,,29\n],
+                 generate_line(["a", "", 29],
                                write_empty_value: nil))
   end
 end