diff --git a/lib/pure/math.nim b/lib/pure/math.nim
index b0104336e1..f63e8c1e59 100644
--- a/lib/pure/math.nim
+++ b/lib/pure/math.nim
@@ -44,6 +44,7 @@ when not defined(js) and not defined(nimscript):
 
 const
   PI* = 3.1415926535897932384626433 ## the circle constant PI (Ludolph's number)
+  TAU* = 6.2831853071795864769252868 ## the circle constant TAU (= 2 * PI)
   E* = 2.71828182845904523536028747 ## Euler's number
 
   MaxFloat64Precision* = 16 ## maximum number of meaningful digits