diff --git a/manager/app/src/main/cpp/ksu.cc b/manager/app/src/main/cpp/ksu.cc
index 54c942c7..8c473edc 100644
--- a/manager/app/src/main/cpp/ksu.cc
+++ b/manager/app/src/main/cpp/ksu.cc
@@ -35,7 +35,7 @@ bool become_manager(const char* pkg) {
     if (userId == 0) {
         sprintf(param, "/data/data/%s", pkg);
     } else {
-        snprintf(param, 10, "/data/user/%d/%s", userId, pkg);
+        snprintf(param, sizeof(param), "/data/user/%d/%s", userId, pkg);
     }
 
     return ksuctl(CMD_BECOME_MANAGER, param, nullptr);