diff --git a/test/bufferutils.js b/test/bufferutils.js
index 414e843..addabd0 100644
--- a/test/bufferutils.js
+++ b/test/bufferutils.js
@@ -37,7 +37,7 @@ describe('bufferutils', function () {
       })
     })
 
-    fixtures.invalid.readUInt64LE.forEach(function (f) {
+    fixtures.invalid.writeUInt64LE.forEach(function (f) {
       it('throws on ' + f.description, function () {
         var buffer = Buffer.alloc(8, 0)
 
diff --git a/test/fixtures/bufferutils.json b/test/fixtures/bufferutils.json
index 0b82d50..b6c13e5 100644
--- a/test/fixtures/bufferutils.json
+++ b/test/fixtures/bufferutils.json
@@ -62,14 +62,39 @@
       {
         "description": "n === 2^53",
         "exception": "RangeError: value out of range",
-        "hex64": "0000000000002000",
+        "hex64": "0000000000002000"
+      },
+      {
+        "description": "n > 2^53",
+        "exception": "RangeError: value out of range",
+        "hex64": "0100000000002000"
+      }
+    ],
+    "writeUInt64LE": [
+      {
+        "description": "n not a number",
+        "exception": "cannot write a non-number as a number",
+        "dec": "foo"
+      },
+      {
+        "description": "n < 0",
+        "exception": "specified a negative value for writing an unsigned value",
+        "dec": -1
+      },
+      {
+        "description": "n === 2^53",
+        "exception": "RangeError: value out of range",
         "dec": 9007199254740992
       },
       {
         "description": "n > 2^53",
         "exception": "RangeError: value out of range",
-        "hex64": "0100000000002000",
         "dec": 9007199254740993
+      },
+      {
+        "description": "floor(n) !== n",
+        "exception": "value has a fractional component",
+        "dec": 1.5
       }
     ]
   }