diff --git a/SC2003.md b/SC2003.md
index 04788a1..3d0f80d 100644
--- a/SC2003.md
+++ b/SC2003.md
@@ -14,6 +14,18 @@ i=$((1+2))
 l=${#var}
 ```
 
+**WARNING:** constants with a leading 0 are interpreted as octal numbers by bash, but not by expr. Then you should specify the base when a leading zero may occur:
+```sh
+$ x=08
+$ echo $(expr 1 + $x)
+9
+$ echo $((1 + $x))
+-bash: 1 + 08: value too great for base (error token is "08")
+$ echo $((1 + 10#$x))
+9
+```
+See [issue #1910](https://github.com/koalaman/shellcheck/issues/1910#issuecomment-610439789)
+
 ### Rationale:
 
 [To quote POSIX:](https://pubs.opengroup.org/onlinepubs/009695399/utilities/expr.html#tag_04_50_17)