diff --git a/doc/api/os.md b/doc/api/os.md
index 06779dbb37cf70..3196efb5b0fc83 100644
--- a/doc/api/os.md
+++ b/doc/api/os.md
@@ -378,9 +378,8 @@ added: v0.3.3
 
 The `os.uptime()` method returns the system uptime in number of seconds.
 
-*Note*: Within Node.js' internals, this number is represented as a `double`.
-However, fractional seconds are not returned and the value can typically be
-treated as an integer.
+*Note*: On Windows the returned value includes fractions of a second.
+Use `Math.floor()` to get whole seconds.
 
 ## os.userInfo([options])
 <!-- YAML
diff --git a/doc/api/process.md b/doc/api/process.md
index e10271060ff5ff..f5cfe8647c3669 100644
--- a/doc/api/process.md
+++ b/doc/api/process.md
@@ -1659,6 +1659,9 @@ added: v0.5.0
 The `process.uptime()` method returns the number of seconds the current Node.js
 process has been running.
 
+*Note*: the return value includes fractions of a second. Use `Math.floor()`
+to get whole seconds.
+
 ## process.version
 <!-- YAML
 added: v0.1.3