diff --git a/SC2009.md b/SC2009.md
index 7b278a0..bc247ed 100644
--- a/SC2009.md
+++ b/SC2009.md
@@ -30,6 +30,8 @@ This is more robust than `ps .. | grep python | cut ..` because it does not try
 
 ### Exceptions
 
+`pgrep` is not POSIX. Please [[ignore]] this warning if you are targeting POSIX userlands.
+
 You can [[ignore]] this error if you are trying to match against something that `pgrep` doesn't support:
 
 ```