diff --git a/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp b/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp
index 02918d2a..998fac80 100644
--- a/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp
+++ b/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp
@@ -2220,8 +2220,9 @@ bool CSteamNetworkingUtils::SetConfigValue( ESteamNetworkingConfigValue eValue,
 		case k_ESteamNetworkingConfig_ConnectionUserData:
 		{
 
-			// We only need special handling when modifying a connection
-			if ( eScopeType != k_ESteamNetworkingConfig_Connection )
+			// We only need special handling when modifying a connection.
+			// Clearing it (NULL) falls through and is rejected by SetConfigValueTyped.
+			if ( eScopeType != k_ESteamNetworkingConfig_Connection || pValue == nullptr )
 				break;
 
 			// Process the user argument, maybe performing type conversion
diff --git a/tests/test_connection.cpp b/tests/test_connection.cpp
index 22d50378..44284160 100644
--- a/tests/test_connection.cpp
+++ b/tests/test_connection.cpp
@@ -1227,6 +1227,9 @@ void Test_pipe()
 		assert( infoBob.m_identityRemote == identAlice );
 	}
 
+	// Connection user data cannot be cleared.  Passing NULL should fail, not crash.
+	assert( !SteamNetworkingUtils()->SetConfigValue( k_ESteamNetworkingConfig_ConnectionUserData, k_ESteamNetworkingConfig_Connection, hAlice, k_ESteamNetworkingConfig_Int64, nullptr ) );
+
 	// Wire up to the global peer state used by TestNetworkConditions / PumpCallbacksAndMakeSureStillConnected.
 	g_peerClient.Reset();
 	g_peerServer.Reset();