diff --git a/lib/write-type.js b/lib/write-type.js
index 94a10ab..ac221ea 100644
--- a/lib/write-type.js
+++ b/lib/write-type.js
@@ -52,29 +52,28 @@ function getWriteType(options) {
   }
 
   function number(encoder, value) {
-    var ivalue = value | 0;
     var type;
-    if (value !== ivalue) {
+    if (Math.floor(value) != value) {
       // float 64 -- 0xcb
       type = 0xcb;
-      token[type](encoder, value);
-      return;
-    } else if (-0x20 <= ivalue && ivalue <= 0x7F) {
+    } else if (-0x20 <= value && value <= 0x7F) {
       // positive fixint -- 0x00 - 0x7f
       // negative fixint -- 0xe0 - 0xff
-      type = ivalue & 0xFF;
-    } else if (0 <= ivalue) {
+      type = value & 0xFF;
+    } else if (0 <= value) {
       // uint 8 -- 0xcc
       // uint 16 -- 0xcd
       // uint 32 -- 0xce
-      type = (ivalue <= 0xFF) ? 0xcc : (ivalue <= 0xFFFF) ? 0xcd : 0xce;
+      // uint 64 -- 0xcf
+      type = (value <= 0xFF) ? 0xcc : (value <= 0xFFFF) ? 0xcd : (value <= 0xFFFFFFFF) ? 0xce : 0xcf;
     } else {
       // int 8 -- 0xd0
       // int 16 -- 0xd1
       // int 32 -- 0xd2
-      type = (-0x80 <= ivalue) ? 0xd0 : (-0x8000 <= ivalue) ? 0xd1 : 0xd2;
+      // int 64 -- 0xd3
+      type = (-0x80 <= value) ? 0xd0 : (-0x8000 <= value) ? 0xd1 : (-0x80000000 <= value) ? 0xd2 : 0xd3;
     }
-    token[type](encoder, ivalue);
+    token[type](encoder, value);
   }
 
   // uint 64 -- 0xcf
diff --git a/test/10.encode.js b/test/10.encode.js
index cc1bfbb..75373b4 100755
--- a/test/10.encode.js
+++ b/test/10.encode.js
@@ -127,7 +127,10 @@ function run_tests(codecopt) {
   it("cc-cf: uint 8/16/32/64", function() {
     assert.deepEqual(toArray(msgpack.encode(0xFF, options)), [0xcc, 0xFF]);
     assert.deepEqual(toArray(msgpack.encode(0xFFFF, options)), [0xcd, 0xFF, 0xFF]);
-    assert.deepEqual(toArray(msgpack.encode(0x7FFFFFFF, options)), [0xce, 0x7F, 0xFF, 0xFF, 0xFF]);
+    assert.deepEqual(toArray(msgpack.encode(0xFFFFFFFF, options)), [0xce, 0xFF, 0xFF, 0xFF, 0xFF]);
+    assert.deepEqual(toArray(msgpack.encode(0x8000000000000000, options)), [0xcf, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
+    assert.notDeepEqual(toArray(msgpack.encode(0x8000000000000001, options)), [0xcf, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01]);
+    assert.notDeepEqual(toArray(msgpack.encode(0xFFFFFFFFFFFFFFFF, options)), [0xcf, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF]);
   });
 
   // int 8 -- 0xd0
@@ -138,6 +141,7 @@ function run_tests(codecopt) {
     assert.deepEqual(toArray(msgpack.encode(-0x80, options)), [0xd0, 0x80]);
     assert.deepEqual(toArray(msgpack.encode(-0x8000, options)), [0xd1, 0x80, 0x00]);
     assert.deepEqual(toArray(msgpack.encode(-0x80000000, options)), [0xd2, 0x80, 0x00, 0x00, 0x00]);
+    assert.notDeepEqual(toArray(msgpack.encode(-0x80000001, options)), [0xd3, 0x80, 0x00, 0x00, 0x01]);
   });
 
   // str 8 -- 0xd9