diff --git a/SC2230.md b/SC2230.md
index dd93d49..8308064 100644
--- a/SC2230.md
+++ b/SC2230.md
@@ -20,6 +20,28 @@ command -v grep
 
 None
 
+### Caveats:
+
+On macOS 10.13.6, command -v appears to take multiple parameters:
+
+```
+# grep is in /usr/bin/grep
+# foobar is not in path
+#
+$ command -v -- grep foobar; echo $?
+0
+```
+
+but succeeds (with exit code 0) if *any* command exists. In the above
+example, it should have failed and exited with 1 unless *all* commands
+exist.
+
+An alternative is:
+
+$ hash <file1> <file2>
+
+Which observes the standard behaviour of failures.
+
 ### Related resources:
 
 * [Check if a program exists from a Bash script](https://stackoverflow.com/a/677212/1899640) on StackOverflow.
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