diff --git a/json.lua b/json.lua
index 40b75c8..4115a53 100644
--- a/json.lua
+++ b/json.lua
@@ -83,7 +83,7 @@ local function encode_number(val)
   if val ~= val or val <= -math.huge or val >= math.huge then
     error("unexpected number value '" .. tostring(val) .. "'")
   end
-  return tostring(val)
+  return string.format("%.14g", val)
 end