diff --git a/src/core/os.c b/src/core/os.c
index 9bc9820f..dcd68a16 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -505,8 +505,11 @@ static int proc_get_status(JanetProc *proc) {
         status = WEXITSTATUS(status);
     } else if (WIFSTOPPED(status)) {
         status = WSTOPSIG(status) + 128;
-    } else {
+    } else if (WIFSIGNALED(status)){
         status = WTERMSIG(status) + 128;
+    } else {
+        /* Could possibly return -1 but for now, just panic */
+        janet_panicf("Undefined status code for process termination, %d.", status);
     }
     return status;
 }