diff --git a/slsDetectorServers/gotthard2DetectorServer/RegisterDefs.h b/slsDetectorServers/gotthard2DetectorServer/RegisterDefs.h
index f94dc511a..cf0d895ed 100644
--- a/slsDetectorServers/gotthard2DetectorServer/RegisterDefs.h
+++ b/slsDetectorServers/gotthard2DetectorServer/RegisterDefs.h
@@ -127,6 +127,7 @@
 
 #define MOD_ID_OFST                         (0)
 #define MOD_ID_MSK                          (0x0000FFFF << MOD_ID_OFST)
+#define MOD_MAX_VAL                         (0xFFFF)
 
 /* ASIC registers --------------------------------------------------*/
 
diff --git a/slsDetectorServers/gotthard2DetectorServer/slsDetectorFunctionList.c b/slsDetectorServers/gotthard2DetectorServer/slsDetectorFunctionList.c
index 8dac4acdc..e1db8b444 100644
--- a/slsDetectorServers/gotthard2DetectorServer/slsDetectorFunctionList.c
+++ b/slsDetectorServers/gotthard2DetectorServer/slsDetectorFunctionList.c
@@ -66,7 +66,6 @@ int64_t burstPeriodReg = 0;
 int filterResistor = 0;
 int cdsGain = 0;
 int detPos[2] = {};
-int64_t serialNumber = -1;
 
 int isInitCheckDone() { return initCheckDone; }
 
@@ -281,21 +280,18 @@ u_int16_t getHardwareVersionNumber() {
             MCB_SERIAL_NO_VRSN_OFST);
 }
 
-u_int32_t getDetectorNumber() {
-    if (serialNumber != -1) {
-        return serialNumber;
-    }
-#ifdef VIRTUAL
-    return 0;
-#endif
-    return bus_r(MCB_SERIAL_NO_REG);
+uint16_t getSerialNumber() {
+    return ((bus_r(MOD_ID_REG) & MOD_ID_MSK) >> MOD_ID_OFST);
 }
 
-void setSerialNumber(int64_t arg) {
-    LOG(logINFOBLUE, ("Setting Serial Number to 0x%llx\n", (long long int)arg));
-    serialNumber = arg;
+void setSerialNumber(uint16_t arg) {
+    LOG(logINFOBLUE, ("Setting Serial Number to 0x%x\n", arg));
+    bus_w(MOD_ID_REG, bus_r(MOD_ID_REG) & ~MOD_ID_MSK);
+    bus_w(MOD_ID_REG, bus_r(MOD_ID_REG) | ((arg << MOD_ID_OFST) & MOD_ID_MSK));
 }
 
+int getMaxSerialNumber() { return MOD_MAX_VAL; }
+
 u_int64_t getDetectorMAC() {
 #ifdef VIRTUAL
     return 0;
diff --git a/slsDetectorServers/slsDetectorServer/include/slsDetectorFunctionList.h b/slsDetectorServers/slsDetectorServer/include/slsDetectorFunctionList.h
index 749cb304c..b9c7b0cc0 100644
--- a/slsDetectorServers/slsDetectorServer/include/slsDetectorFunctionList.h
+++ b/slsDetectorServers/slsDetectorServer/include/slsDetectorFunctionList.h
@@ -94,7 +94,9 @@ void readDetectorNumber();
 #endif
 u_int32_t getDetectorNumber();
 #ifdef GOTTHARD2D
-void setSerialNumber(int64_t arg);
+uint16_t getSerialNumber();
+void setSerialNumber(uint16_t arg);
+int getMaxSerialNumber();
 #endif
 u_int64_t getDetectorMAC();
 u_int32_t getDetectorIP();
diff --git a/slsDetectorServers/slsDetectorServer/src/slsDetectorServer_funcs.c b/slsDetectorServers/slsDetectorServer/src/slsDetectorServer_funcs.c
index 080e2d7df..fc8f03a2c 100644
--- a/slsDetectorServers/slsDetectorServer/src/slsDetectorServer_funcs.c
+++ b/slsDetectorServers/slsDetectorServer/src/slsDetectorServer_funcs.c
@@ -666,7 +666,11 @@ int get_serial_number(int file_des) {
     ret = OK;
     memset(mess, 0, sizeof(mess));
     int64_t retval = -1;
+#ifdef GOTTHARD2D
+    retval = getSerialNumber();
+#else
     retval = getDetectorNumber();
+#endif
     LOG(logDEBUG1, ("detector number retval: 0x%llx\n", (long long int)retval));
     return Server_SendResult(file_des, INT64, &retval, sizeof(retval));
 }
@@ -683,7 +687,14 @@ int set_serial_number(int file_des) {
 #ifndef GOTTHARD2D
     functionNotImplemented();
 #else
-    setSerialNumber(arg);
+    if (arg > getMaxSerialNumber()) {
+        ret = FAIL;
+        sprintf(mess, "Could not set serial number. Max value: %d\n",
+                getMaxSerialNumber());
+        LOG(logERROR, (mess));
+    } else {
+        setSerialNumber(arg);
+    }
 #endif
     return Server_SendResult(file_des, INT64, NULL, 0);
 }
diff --git a/slsDetectorSoftware/src/CmdProxy.cpp b/slsDetectorSoftware/src/CmdProxy.cpp
index 1a7e60e97..6dc2ba458 100644
--- a/slsDetectorSoftware/src/CmdProxy.cpp
+++ b/slsDetectorSoftware/src/CmdProxy.cpp
@@ -261,8 +261,7 @@ std::string CmdProxy::SerialNumber(int action) {
     std::ostringstream os;
     os << cmd << ' ';
     if (action == slsDetectorDefs::HELP_ACTION)
-        os << "\n\tSerial number of detector.\n\t[Gotthard2] Can overwrite, "
-              "but must do so for every detector server restart."
+        os << "\n\tSerial number of detector.\n\t[Gotthard2] Can overwrite"
            << '\n';
     else if (action == slsDetectorDefs::GET_ACTION) {
         if (!args.empty()) {
diff --git a/slsDetectorSoftware/tests/test-CmdProxy.cpp b/slsDetectorSoftware/tests/test-CmdProxy.cpp
index d8c882713..01769f57a 100644
--- a/slsDetectorSoftware/tests/test-CmdProxy.cpp
+++ b/slsDetectorSoftware/tests/test-CmdProxy.cpp
@@ -107,11 +107,14 @@ TEST_CASE("serialnumber", "[.cmd]") {
     REQUIRE_NOTHROW(proxy.Call("serialnumber", {}, -1, GET));
     if (det.getDetectorType().squash() == defs::GOTTHARD2) {
         auto prev_val = det.getSerialNumber();
-        std::ostringstream oss1, oss2;
+        std::ostringstream oss1, oss2, oss3;
         proxy.Call("serialnumber", {"0x5d"}, -1, PUT, oss1);
         REQUIRE(oss1.str() == "serialnumber 0x5d\n");
         proxy.Call("serialnumber", {}, -1, GET, oss2);
         REQUIRE(oss2.str() == "serialnumber 0x5d\n");
+        proxy.Call("serialnumber", {"0xffff"}, -1, PUT, oss3);
+        REQUIRE(oss3.str() == "serialnumber 0xffff\n");
+        REQUIRE_THROWS(proxy.Call("serialnumber", {"65536"}, -1, PUT));
         for (int i = 0; i != det.size(); ++i) {
             det.setSerialNumber(prev_val[i], {i});
         }