diff --git a/lib/psych.rb b/lib/psych.rb
index 850a6d19..6139d1be 100644
--- a/lib/psych.rb
+++ b/lib/psych.rb
@@ -623,7 +623,7 @@ def self.dump_stream *objects
   def self.to_json object
     visitor = Psych::Visitors::JSONTree.create
     visitor << object
-    visitor.tree.yaml
+    visitor.tree.yaml(nil, line_width: -1)
   end
 
   ###
diff --git a/test/psych/test_json_tree.rb b/test/psych/test_json_tree.rb
index 37c05075..b1c6efb3 100644
--- a/test/psych/test_json_tree.rb
+++ b/test/psych/test_json_tree.rb
@@ -7,6 +7,16 @@ def test_string
       assert_match(/"foo"/, Psych.to_json("foo"))
     end
 
+    def test_long_string
+      string = 'word ' * 30
+      assert_equal "\"#{string}\"\n", Psych.to_json(string)
+    end
+
+    def test_long_string_in_sequence
+      string = 'word ' * 30
+      assert_include Psych.to_json([[1, string]]), "\"#{string}\""
+    end
+
     def test_symbol
       assert_match(/"foo"/, Psych.to_json(:foo))
     end