diff --git a/src/core/os.c b/src/core/os.c
index 58adc668..d6c55a1c 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -427,9 +427,11 @@ static int janet_proc_mark(void *p, size_t s) {
 }
 
 #ifdef JANET_EV
-JANET_NO_RETURN
+static JANET_NO_RETURN void
+#else
+static Janet
 #endif
-static Janet os_proc_wait_impl(JanetProc *proc) {
+os_proc_wait_impl(JanetProc *proc) {
     if (proc->flags & (JANET_PROC_WAITED | JANET_PROC_WAITING)) {
         janet_panicf("cannot wait twice on a process");
     }