diff --git a/internal/core/src/segcore/metrics_c.cpp b/internal/core/src/segcore/metrics_c.cpp
index cffa09e1b75d7cbfc91d6eccf5cae8ac0312b13d..2a754f75b6d5a7f8d8b05dd286959bcb95672a75 100644
--- a/internal/core/src/segcore/metrics_c.cpp
+++ b/internal/core/src/segcore/metrics_c.cpp
@@ -20,5 +20,6 @@ GetKnowhereMetrics() {
     auto len = str.length();
     char* res = (char*)malloc(len + 1);
     memcpy(res, str.data(), len);
+    res[len] = '\0';
     return res;
 }