diff --git a/lib/ComputeM34.cpp b/lib/ComputeM34.cpp
index 8c92b8d..2e83c04 100644
--- a/lib/ComputeM34.cpp
+++ b/lib/ComputeM34.cpp
@@ -337,7 +337,7 @@ bool ComputeM3::GetM33_2()
     bool ret = true;
     GetM3_X(REGISTRY_DNS_LeakedTLD, &m33_2, 0.001);
 
-    for (int i = 0; i < m33_2.size(); i++) {
+    for (size_t i = 0; i < m33_2.size(); i++) {
         if (strcmp(m33_2[i].domain, "ARPA") == 0) {
             m33_2.erase(m33_2.begin() + i);
             break;