diff --git a/src/gps/RTC.cpp b/src/gps/RTC.cpp
index a93a1ff62..ad26b55a4 100644
--- a/src/gps/RTC.cpp
+++ b/src/gps/RTC.cpp
@@ -435,6 +435,7 @@ time_t gm_mktime(const struct tm *tm)
 
     return result;
 #else
-    return mktime(tm);
+    struct tm tmCopy = *tm;
+    return mktime(&tmCopy);
 #endif
 }