diff --git a/SC2308.md b/SC2308.md
index c9be31e..0ddf239 100644
--- a/SC2308.md
+++ b/SC2308.md
@@ -63,7 +63,7 @@ otherwise, you can find the index of the first `=` using parameter expansion and
 ```
 str="mykey=myvalue"
 x=${str%%=*}     # Assign x="mystr"
-index=$((x+1))   # Add 1 to length of x
+index=$((${#x}+1))   # Add 1 to length of x
 ```
 
 #### `substr`