diff --git a/sh/sum b/sh/sum
index 24f7937..cc26777 100755
--- a/sh/sum
+++ b/sh/sum
@@ -16,6 +16,7 @@ sum() { ### @-
     ### **TODO:** consider renaming because sum(1) already exists.
     local sum=0
     for i; do
+        i="${i%,}"
         : $((sum+=i))
     done
     echo "$sum"