diff --git a/payload_consumer/payload_metadata.cc b/payload_consumer/payload_metadata.cc
index 01f3b62..2cb73eb 100644
--- a/payload_consumer/payload_metadata.cc
+++ b/payload_consumer/payload_metadata.cc
@@ -18,6 +18,7 @@
 
 #include <endian.h>
 
+#include <base/strings/stringprintf.h>
 #include <brillo/data_encoding.h>
 
 #include "update_engine/common/constants.h"
@@ -55,7 +56,18 @@
 
   // Validate the magic string.
   if (memcmp(payload.data(), kDeltaMagic, sizeof(kDeltaMagic)) != 0) {
-    LOG(ERROR) << "Bad payload format -- invalid delta magic.";
+    LOG(ERROR) << "Bad payload format -- invalid delta magic: "
+               << base::StringPrintf("%02x%02x%02x%02x",
+                                     payload[0],
+                                     payload[1],
+                                     payload[2],
+                                     payload[3])
+               << " Expected: "
+               << base::StringPrintf("%02x%02x%02x%02x",
+                                     kDeltaMagic[0],
+                                     kDeltaMagic[1],
+                                     kDeltaMagic[2],
+                                     kDeltaMagic[3]);
     *error = ErrorCode::kDownloadInvalidMetadataMagicString;
     return MetadataParseResult::kError;
   }