diff --git a/res/modules/internal/extensions/math.lua b/res/modules/internal/extensions/math.lua
index d906e94a2..df0eadf72 100644
--- a/res/modules/internal/extensions/math.lua
+++ b/res/modules/internal/extensions/math.lua
@@ -35,3 +35,7 @@ function math.sum(...)
 
     return sum
 end
+
+function math.sign(x)
+    return (x > 0) and 1 or (x < 0 and -1 or 0)
+end