diff --git a/src/stratum_server.cpp b/src/stratum_server.cpp
index 5e8da32..b72fea7 100644
--- a/src/stratum_server.cpp
+++ b/src/stratum_server.cpp
@@ -438,7 +438,13 @@ bool StratumServer::on_submit(StratumClient* client, uint32_t id, const char* jo
 
 		if (target >= TARGET_4_BYTES_LIMIT) {
 			// "Low diff share" fix: adjust target to the same value as XMRig would use
-			target = std::numeric_limits<uint64_t>::max() / (std::numeric_limits<uint32_t>::max() / (target >> 32));
+			const uint64_t upper_bits = target >> 32;
+			if (upper_bits > 0) {
+				const uint64_t divisor = std::numeric_limits<uint32_t>::max() / upper_bits;
+				if (divisor > 0) {
+					target = std::numeric_limits<uint64_t>::max() / divisor;
+				}
+			}
 		}
 
 		SubmittedShare share{};
diff --git a/src/wallet.cpp b/src/wallet.cpp
index 7e4e881..368a274 100644
--- a/src/wallet.cpp
+++ b/src/wallet.cpp
@@ -202,13 +202,13 @@ bool Wallet::decode(const char* address)
         {
             char spend_hex[65] = {0}, view_hex[65] = {0}, data_hex[200] = {0}, prefix_hex[20] = {0};
             for (int i = 0; i < 32; i++) {
-                sprintf(spend_hex + static_cast<ptrdiff_t>(i)*2, "%02x", m_spendPublicKey.h[i]);
-                sprintf(view_hex + static_cast<ptrdiff_t>(i)*2, "%02x", m_viewPublicKey.h[i]);
+                snprintf(spend_hex + static_cast<ptrdiff_t>(i)*2, sizeof(spend_hex) - static_cast<size_t>(i)*2, "%02x", m_spendPublicKey.h[i]);
+                snprintf(view_hex + static_cast<ptrdiff_t>(i)*2, sizeof(view_hex) - static_cast<size_t>(i)*2, "%02x", m_viewPublicKey.h[i]);
             }
             for (int i = 0; i < std::min(data_index, 80); i++) {
-                sprintf(data_hex + static_cast<ptrdiff_t>(i)*2, "%02x", data[i]);
+                snprintf(data_hex + static_cast<ptrdiff_t>(i)*2, sizeof(data_hex) - static_cast<size_t>(i)*2, "%02x", data[i]);
             }
-            sprintf(prefix_hex, "0x%llx", static_cast<unsigned long long>(m_prefix));
+            snprintf(prefix_hex, sizeof(prefix_hex), "0x%llx", static_cast<unsigned long long>(m_prefix));
             LOGINFO(6, "decode varint_len=" << varint_len << " data_index=" << data_index << " prefix=" << static_cast<const char*>(prefix_hex));
             LOGINFO(6, "decode raw_data: " << static_cast<const char*>(data_hex));
             LOGINFO(6, "decode spend:    " << static_cast<const char*>(spend_hex));