diff --git a/sdk/Windows/Helpers.cpp b/sdk/Windows/Helpers.cpp
index 1fb8021..0700b11 100644
--- a/sdk/Windows/Helpers.cpp
+++ b/sdk/Windows/Helpers.cpp
@@ -202,6 +202,22 @@ double SMX::GetMonotonicTime()
     return iTime / 10000000.0;
 }
 
+void SMX::GenerateRandom(void *pOut, int iSize)
+{
+    // These calls shouldn't fail.
+    HCRYPTPROV cryptProv;
+    if(!CryptAcquireContext(&cryptProv, nullptr,
+        L"Microsoft Base Cryptographic Provider v1.0",
+        PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
+        throw exception("CryptAcquireContext error");
+
+    if(!CryptGenRandom(cryptProv, iSize, (BYTE *) pOut)) 
+        throw exception("CryptGenRandom error");
+
+    if(!CryptReleaseContext(cryptProv, 0))
+        throw exception("CryptReleaseContext error");
+}
+
 const char *SMX::CreateError(string error)
 {
     // Store the string in a static so it doesn't get deallocated.
diff --git a/sdk/Windows/Helpers.h b/sdk/Windows/Helpers.h
index b9b90f8..8b5dddf 100644
--- a/sdk/Windows/Helpers.h
+++ b/sdk/Windows/Helpers.h
@@ -26,6 +26,7 @@ string BinaryToHex(const void *pData_, int iNumBytes);
 string BinaryToHex(const string &sString);
 bool GetRandomBytes(void *pData, int iBytes);
 double GetMonotonicTime();
+void GenerateRandom(void *pOut, int iSize);
 
 // Create a char* string that will be valid until the next call to CreateError.
 // This is used to return error messages to the caller.
diff --git a/sdk/Windows/SMX.cpp b/sdk/Windows/SMX.cpp
index 4df2ac9..a943199 100644
--- a/sdk/Windows/SMX.cpp
+++ b/sdk/Windows/SMX.cpp
@@ -99,5 +99,6 @@ SMX_API void SMX_SetLights2(const char *lightData, int lightDataSize)
 SMX_API void SMX_ReenableAutoLights() { SMXManager::g_pSMX->ReenableAutoLights(); }
 SMX_API const char *SMX_Version() { return SMX_BUILD_VERSION; }
 
-// This isn't exposed in the public API, since this is only used internally.
+// These aren't exposed in the public API, since they're only used internally.
 SMX_API void SMX_SetOnlySendLightsOnChange(bool value) { SMXManager::g_pSMX->SetOnlySendLightsOnChange(value); }
+SMX_API void SMX_SetSerialNumbers() { SMXManager::g_pSMX->SetSerialNumbers(); }
diff --git a/sdk/Windows/SMXManager.cpp b/sdk/Windows/SMXManager.cpp
index d39388e..952996d 100644
--- a/sdk/Windows/SMXManager.cpp
+++ b/sdk/Windows/SMXManager.cpp
@@ -581,6 +581,29 @@ void SMX::SMXManager::UpdatePanelTestMode()
         m_pDevices[iPad]->SendCommandLocked(ssprintf("t %c\n", m_PanelTestMode));
 }
 
+// Assign a serial number to master controllers if one isn't already assigned.  This
+// will have no effect if a serial is already set.
+//
+// We just assign a random number.  The serial number will be used as the USB serial
+// number, and can be queried in SMXInfo.
+void SMX::SMXManager::SetSerialNumbers()
+{
+    g_Lock.AssertNotLockedByCurrentThread();
+    LockMutex L(g_Lock);
+
+    m_aPendingLightsCommands.clear();
+    for(int iPad = 0; iPad < 2; ++iPad)
+    {
+        string sData = "s";
+        uint8_t serial[16];
+        SMX::GenerateRandom(serial, sizeof(serial));
+        sData.append((char *) serial, sizeof(serial));
+        sData.append(1, '\n');
+
+        m_pDevices[iPad]->SendCommandLocked(sData);
+    }
+}
+
 void SMX::SMXManager::RunInHelperThread(function<void()> func)
 {
     m_UserCallbackThread.RunInThread(func);
diff --git a/sdk/Windows/SMXManager.h b/sdk/Windows/SMXManager.h
index cf64fe0..9154061 100644
--- a/sdk/Windows/SMXManager.h
+++ b/sdk/Windows/SMXManager.h
@@ -46,6 +46,7 @@ public:
     void SetLights(const string sLights[2]);
     void ReenableAutoLights();
     void SetPanelTestMode(PanelTestMode mode);
+    void SetSerialNumbers();
     void SetOnlySendLightsOnChange(bool value) { m_bOnlySendLightsOnChange = value; }
     
     // Run a function in the user callback thread.