diff --git a/lib/system.nim b/lib/system.nim
index 2a5f13b73..869bdc9b4 100644
--- a/lib/system.nim
+++ b/lib/system.nim
@@ -1499,7 +1499,7 @@ const
     ## Contains an IEEE floating point value of *Not A Number*.
     ##
     ## Note that you cannot compare a floating point value to this value
-    ## and expect a reasonable result - use the `classify` procedure
+    ## and expect a reasonable result - use the `isNaN` or `classify` procedure
     ## in the `math module <math.html>`_ for checking for NaN.