diff --git a/lib/stdlib/doc/src/math.xml b/lib/stdlib/doc/src/math.xml
index 19b72eb01389..9f9903180568 100644
--- a/lib/stdlib/doc/src/math.xml
+++ b/lib/stdlib/doc/src/math.xml
@@ -110,7 +110,7 @@ erf(X) = 2/sqrt(pi)*integral from 0 to X of exp(-t*t) dt.</pre>
     </func>
 
     <func>
-      <name name="tau" arity="0" since=""/>
+      <name name="tau" arity="0" since="OTP @OTP-18361@"/>
       <fsummary>Ratio of the circumference of a circle to its radius.</fsummary>
       <desc>
         <p>Ratio of the circumference of a circle to its radius.</p>