diff --git a/src/core/os.c b/src/core/os.c
index 1fcd2102..bc82bf46 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -853,7 +853,8 @@ static void janet_signal_trampoline(int sig) {
 
 JANET_CORE_FN(os_sigaction,
               "(os/sigaction which &opt handler interrupt-interpreter)",
-              "Add a signal handler for a given action. Use nil for the `handler` argument to remove a signal handler.") {
+              "Add a signal handler for a given action. Use nil for the `handler` argument to remove a signal handler. "
+              "All signal handlers are the same as supported by `os/proc-kill`.") {
     janet_sandbox_assert(JANET_SANDBOX_SIGNAL);
     janet_arity(argc, 1, 3);
 #ifdef JANET_WINDOWS