diff --git a/inc/post_code.hpp b/inc/post_code.hpp
index 26b5c48..db7533f 100644
--- a/inc/post_code.hpp
+++ b/inc/post_code.hpp
@@ -50,7 +50,7 @@
     }
 };
 using EventPtr = std::unique_ptr<sd_event, EventDeleter>;
-using primarycode_t = uint64_t;
+using primarycode_t = std::vector<uint8_t>;
 using secondarycode_t = std::vector<uint8_t>;
 using postcode_t = std::tuple<primarycode_t, secondarycode_t>;
 namespace fs = std::filesystem;
diff --git a/src/post_code.cpp b/src/post_code.cpp
index 037f293..6473562 100644
--- a/src/post_code.cpp
+++ b/src/post_code.cpp
@@ -119,16 +119,22 @@
             POSTCODE_DISPLAY_PATH + std::to_string(node);
 
         std::ofstream postCodeDisplayFile(postCodeDisplayPath);
-        postCodeDisplayFile << "0x" << std::setfill('0') << std::setw(2)
-                            << std::hex << std::get<0>(code);
+        postCodeDisplayFile << "0x" << std::setfill('0') << std::hex;
+        for (const auto& byte : std::get<0>(code))
+        {
+            postCodeDisplayFile << std::setw(2) << static_cast<int>(byte);
+        }
         postCodeDisplayFile.close();
     }
 
 #ifdef ENABLE_BIOS_POST_CODE_LOG
     uint64_t usTimeOffset = tsUS - firstPostCodeUsSinceEpoch;
     std::ostringstream hexCode;
-    hexCode << "0x" << std::setfill('0') << std::setw(2) << std::hex
-            << std::get<0>(code);
+    hexCode << "0x" << std::setfill('0') << std::hex;
+    for (const auto& byte : std::get<0>(code))
+    {
+        hexCode << std::setw(2) << static_cast<int>(byte);
+    }
 
     std::ostringstream timeOffsetStr;
     // Set Fixed-Point Notation