diff --git a/help/cbot/E/tan.txt b/help/cbot/E/tan.txt
index ecc605fa..0e0243c7 100644
--- a/help/cbot/E/tan.txt
+++ b/help/cbot/E/tan.txt
@@ -3,7 +3,7 @@ Syntax:
 \s;\c;tan ( angle );\n;
 
 \t;angle: \c;\l;float\u cbot\float;\n;
-Angle in degrees.
+Angle in degrees (except multiples of 90).
 
 \t;Return value: \c;\l;float\u cbot\float;\n;
 Tangent of the angle.