diff --git a/include/kabufuda/Card.hpp b/include/kabufuda/Card.hpp
index 6b16324..1aa9ea7 100644
--- a/include/kabufuda/Card.hpp
+++ b/include/kabufuda/Card.hpp
@@ -334,11 +334,10 @@ public:
     const uint8_t* getCurrentMaker() const;
 
     /**
-     * @brief Retrieves the format assigned serial in two 32bit parts
-     * @param s0
-     * @param s1
+     * @brief Retrieves the format assigned serial
+     * @param serial
      */
-    void getSerial(uint32_t* s0, uint32_t* s1);
+    void getSerial(uint64_t& serial);
 
     /**
      * @brief Retrieves the checksum values of the Card system header
diff --git a/lib/kabufuda/Card.cpp b/lib/kabufuda/Card.cpp
index d63eaf3..622a244 100644
--- a/lib/kabufuda/Card.cpp
+++ b/lib/kabufuda/Card.cpp
@@ -645,13 +645,15 @@ const uint8_t* Card::getCurrentMaker() const
     return nullptr;
 }
 
-void Card::getSerial(uint32_t* s0, uint32_t* s1)
+void Card::getSerial(uint64_t& serial)
 {
-    uint32_t serial[8];
+    Card copy = *this;
+    copy._swapEndian();
+    uint32_t serialBuf[8];
     for (uint32_t i = 0; i < 8; i++)
-        memcpy(&serial[i], reinterpret_cast<uint8_t*>(m_serial + (i * 4)), 4);
-    *s0 = serial[0] ^ serial[2] ^ serial[4] ^ serial[6];
-    *s1 = serial[1] ^ serial[3] ^ serial[5] ^ serial[7];
+        serialBuf[i] = SBig(*reinterpret_cast<uint32_t*>(copy.__raw + (i * 4)));
+    serial = uint64_t(serialBuf[0] ^ serialBuf[2] ^ serialBuf[4] ^ serialBuf[6]) << 32 |
+             (serialBuf[1] ^ serialBuf[3] ^ serialBuf[5] ^ serialBuf[7]);
 }
 
 void Card::getChecksum(uint16_t* checksum, uint16_t* inverse)
diff --git a/test/main.cpp b/test/main.cpp
index ef7abfe..e1e99f9 100644
--- a/test/main.cpp
+++ b/test/main.cpp
@@ -6,6 +6,9 @@ int main()
     kabufuda::Card mc{_S("test.USA.raw"), "GM8E", "01"};
     if (!mc)
         mc.format(kabufuda::EDeviceId::SlotA, kabufuda::ECardSize::Card2043Mb);
+    uint64_t a = 0;
+    mc.getSerial(a);
+
     kabufuda::Card mc2{_S("test2.USA.raw"), "GM8E", "01"};
     if (!mc2)
         mc2.format(kabufuda::EDeviceId::SlotA, kabufuda::ECardSize::Card2043Mb);
@@ -19,6 +22,7 @@ int main()
         mc.setCanMove(f, true);
     }
 
+
     if (f)
     {
         mc.setBannerFormat(f, kabufuda::EImageFormat::C8);