diff --git a/bash/tickertape b/bash/tickertape
index 737cb62..8768337 100755
--- a/bash/tickertape
+++ b/bash/tickertape
@@ -4,7 +4,7 @@ cols=$(tput cols) line=""
 
 while (( ${#line} < cols + ${#1} )); do
   if (( ${#line} < ${#1} )); then
-    line=${1:$(( ${#1} - ${#line} - 1)):1}$line
+    line=${1:$((${#1}-${#line}-1)):1}$line
   else
     line=" $line"
   fi