diff --git a/ChangeLog b/ChangeLog
index d79692ffa..2a7350f09 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2014-01-07  Quentin Mathe <quentin.mathe@gmail.com>
+
+	* Source/NSJSONSerialization.m (writeObject()): Fixed double number 
+	serialization to encode 17 significant digits (this matches the max number 
+	of significant digits in the double-precision floating point format). This 
+	prevents a loss of precision, in case the number has more than 3 digits 
+	after the decimal point.
+	* Tests/base/NSJSONSerialization/json.m: Updated to test double number  
+	serialization. 
+
 2014-01-07  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/NSOperation.m: Make sure current queue is set for threads
diff --git a/Source/NSJSONSerialization.m b/Source/NSJSONSerialization.m
index 17a9ebacc..83d6b299f 100644
--- a/Source/NSJSONSerialization.m
+++ b/Source/NSJSONSerialization.m
@@ -901,7 +901,7 @@ writeObject(id obj, NSMutableString *output, NSInteger tabs)
         }
       else
         {
-          [output appendFormat: @"%g", [(NSNumber*)obj doubleValue]];
+          [output appendFormat: @"%.17g", [(NSNumber*)obj doubleValue]];
         }
     }
   else if ([obj isKindOfClass: NSNullClass])
diff --git a/Tests/base/NSJSONSerialization/json.m b/Tests/base/NSJSONSerialization/json.m
index 275eeca1f..6bbfe06a2 100644
--- a/Tests/base/NSJSONSerialization/json.m
+++ b/Tests/base/NSJSONSerialization/json.m
@@ -21,6 +21,7 @@ int main(void)
   \"emptyString\":\"\",\"emptyArray\":[],\"emptyObject\":{},\
   \"IDs\": [116, 943, 234, 38793],\
   \"escapeTest\": \"\\\"\\u0001\"\
+  \"double\": 123.456789012254,\
 }";
   NSStringEncoding encs[] = {\
     NSUTF8StringEncoding,\
@@ -48,7 +49,7 @@ int main(void)
       obj = tmp;
     }
 
-  PASS([obj count] == 6,
+  PASS([obj count] == 7,
     "Decoded dictionary had the right number of elements");
   PASS([NSJSONSerialization isValidJSONObject: obj],
     "Can serialise deserialised JSON");