diff --git a/SC3015.md b/SC3015.md
index f2d4874..d8a386a 100644
--- a/SC3015.md
+++ b/SC3015.md
@@ -18,7 +18,7 @@ expr "$var" : ".*foo[0-9]*" > /dev/null
 
 You are using `=~` in a script declared to be compatible with POSIX sh or Dash.
 
-`=~` is not a POSIX operator and is unlikely to outside `[[ ]]` in Bash and Ksh.
+`=~` is [not a POSIX operator](https://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html) and is unlikely to work outside `[[ ]]` in Bash and Ksh.
 
 Use `expr`'s `:` operator instead.