diff --git a/lib/instrument/visitors/function.js b/lib/instrument/visitors/function.js
index fa48a0ab..8541e773 100644
--- a/lib/instrument/visitors/function.js
+++ b/lib/instrument/visitors/function.js
@@ -577,6 +577,9 @@ function hoistSloppyFunctionDeclaration(declaration) {
 	// In CommonJS code, file block is CommonJS wrapper function's params, and in any other context
 	// file block contains no bindings except `this`. So it's safe to treat as a params block in all cases.
 	// NB: `paramsBlockBinding.argNames` check is to avoid the pseudo-param `arguments` blocking hoisting.
+	// An actual param called `arguments` *does* prevent hoisting.
+	// e.g. `function f(arguments) { { function arguments() {} } return arguments; }`
+	// returns the value outer function is called with, not the inner function.
 	const paramsBlockBinding = hoistBlock.parent.bindings.get(varName);
 	if (paramsBlockBinding && !paramsBlockBinding.argNames) return;