diff --git a/bootstat/bootstat.cpp b/bootstat/bootstat.cpp
index da1e9d8..07d410c 100644
--- a/bootstat/bootstat.cpp
+++ b/bootstat/bootstat.cpp
@@ -477,8 +477,10 @@
         if (subReason != "") {  // Will not land "reboot" as that is too blunt.
           if (isKernelRebootReason(subReason)) {
             ret = "reboot," + subReason;  // User space can't talk kernel reasons.
-          } else {
+          } else if (isKnownRebootReason(subReason)) {
             ret = subReason;
+          } else {
+            ret = "reboot," + subReason;  // legitimize unknown reasons
           }
         }
       }