diff --git a/src/NimBLEAdvertisementData.cpp b/src/NimBLEAdvertisementData.cpp
index c2372f5..b0f28ff 100644
--- a/src/NimBLEAdvertisementData.cpp
+++ b/src/NimBLEAdvertisementData.cpp
@@ -223,7 +223,7 @@ bool NimBLEAdvertisementData::removeServiceUUID(const NimBLEUUID& serviceUUID) {
     }
 
     int uuidLoc = -1;
-    for (int i = dataLoc + 2; i < m_payload.size(); i += bytes) {
+    for (size_t i = dataLoc + 2; i < m_payload.size(); i += bytes) {
         if (memcmp(&m_payload[i], serviceUUID.getValue(), bytes) == 0) {
             uuidLoc = i;
             break;
@@ -519,7 +519,7 @@ bool NimBLEAdvertisementData::setServiceData(const NimBLEUUID& uuid, const std::
  * @return -1 if the data is not found, otherwise the index of the data in the payload.
  */
 int NimBLEAdvertisementData::getDataLocation(uint8_t type) const {
-    int index = 0;
+    size_t index = 0;
     while (index < m_payload.size()) {
         if (m_payload[index + 1] == type) {
             return index;
diff --git a/src/NimBLEExtAdvertising.cpp b/src/NimBLEExtAdvertising.cpp
index 7421f85..aa016cc 100644
--- a/src/NimBLEExtAdvertising.cpp
+++ b/src/NimBLEExtAdvertising.cpp
@@ -765,7 +765,7 @@ bool NimBLEExtAdvertisement::removeServiceUUID(const NimBLEUUID& serviceUUID) {
     }
 
     int uuidLoc = -1;
-    for (int i = dataLoc + 2; i < m_payload.size(); i += bytes) {
+    for (size_t i = dataLoc + 2; i < m_payload.size(); i += bytes) {
         if (memcmp(&m_payload[i], serviceUUID.getValue(), bytes) == 0) {
             uuidLoc = i;
             break;
@@ -1019,7 +1019,7 @@ void NimBLEExtAdvertisement::addTxPower() {
  * @return -1 if the data is not found, otherwise the index of the data in the payload.
  */
 int NimBLEExtAdvertisement::getDataLocation(uint8_t type) const {
-    int index = 0;
+    size_t index = 0;
     while (index < m_payload.size()) {
         if (m_payload[index + 1] == type) {
             return index;