diff --git a/script/st b/script/st
index e3ea463..245f5e4 100755
--- a/script/st
+++ b/script/st
@@ -186,7 +186,7 @@ file or standard input.
   --min                 # minimum
   --max                 # maximum
   --mean|average|avg|m  # mean
-  --stdev|sd            # standard deviation
+  --stddev|sd            # standard deviation
   --stderr|sem|se       # standard error of mean
   --sum|s               # sum of elements of the sample
   --variance|var        # variance