diff --git a/PlayTools/PlayLoader.m b/PlayTools/PlayLoader.m
index 1e1c6cce..ef2a15ba 100644
--- a/PlayTools/PlayLoader.m
+++ b/PlayTools/PlayLoader.m
@@ -90,6 +90,7 @@ static int my_sysctlbyname(const char *name, void *oldp, size_t *oldlenp, void *
       int ret = sysctlbyname(name, oldp, oldlenp, newp, newlen);
       const char *mechine = DEVICE_MODEL;
       strncpy((char *)oldp, mechine, strlen(mechine));
+      *oldlenp = strlen(mechine);
       return ret;
     } else {
       int ret = sysctlbyname(name, oldp, oldlenp, newp, newlen);
@@ -100,6 +101,7 @@ static int my_sysctlbyname(const char *name, void *oldp, size_t *oldlenp, void *
       int ret = sysctlbyname(name, oldp, oldlenp, newp, newlen);
       const char *mechine = OEM_ID;
       strncpy((char *)oldp, mechine, strlen(mechine));
+      *oldlenp = strlen(mechine);
       return ret;
     } else {
       int ret = sysctlbyname(name, oldp, oldlenp, newp, newlen);