diff --git a/src/dns.cpp b/src/dns.cpp
index 1704d51..5bf8bd8 100644
--- a/src/dns.cpp
+++ b/src/dns.cpp
@@ -52,7 +52,7 @@ using Tins::Memory::OutputMemoryStream;
 namespace Tins {
 
 PDU::metadata DNS::extract_metadata(const uint8_t *buffer, uint32_t total_sz) {
-    if (TINS_UNLIKELY(sizeof(dns_header))) {
+    if (TINS_UNLIKELY(total_sz < sizeof(dns_header))) {
         throw malformed_packet();
     }
     return metadata(total_sz, pdu_flag, PDU::UNKNOWN);