diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index aecc6874d80c6d..a7729e9f2e8de6 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -794,14 +794,14 @@ void WriteFloatGeneric(const FunctionCallbackInfo<Value>& args) {
   size_t offset = args[2]->IntegerValue(env->context()).FromMaybe(0);
 
   size_t memcpy_num = sizeof(T);
-  if (offset + sizeof(T) > ts_obj_length)
-    memcpy_num = ts_obj_length - offset;
 
   if (should_assert) {
     CHECK_NOT_OOB(offset + memcpy_num >= memcpy_num);
     CHECK_NOT_OOB(offset + memcpy_num <= ts_obj_length);
   }
-  CHECK_LE(offset + memcpy_num, ts_obj_length);
+
+  if (offset + memcpy_num > ts_obj_length)
+    memcpy_num = ts_obj_length - offset;
 
   union NoAlias {
     T val;
diff --git a/test/parallel/test-buffer.js b/test/parallel/test-buffer.js
index 8d42bea82d5e8c..c833a9b0c68c31 100644
--- a/test/parallel/test-buffer.js
+++ b/test/parallel/test-buffer.js
@@ -1041,6 +1041,16 @@ assert.throws(function() {
   new Buffer(0xFFFFFFFFF);
 }, RangeError);
 
+// issue GH-5587
+assert.throws(function() {
+  var buf = new Buffer(8);
+  buf.writeFloatLE(0, 5);
+}, RangeError);
+assert.throws(function() {
+  var buf = new Buffer(16);
+  buf.writeDoubleLE(0, 9);
+}, RangeError);
+
 
 // attempt to overflow buffers, similar to previous bug in array buffers
 assert.throws(function() {