diff --git a/src/terminal/parser/ut_parser/InputEngineTest.cpp b/src/terminal/parser/ut_parser/InputEngineTest.cpp
index 19aa93919e9..dcae5bcb815 100644
--- a/src/terminal/parser/ut_parser/InputEngineTest.cpp
+++ b/src/terminal/parser/ut_parser/InputEngineTest.cpp
@@ -554,11 +554,6 @@ void InputEngineTest::AlphanumericTest()
 
 void InputEngineTest::RoundTripTest()
 {
-    // TODO GH #4405: This test fails.
-    Log::Result(WEX::Logging::TestResults::Skipped);
-    return;
-
-    /*
     auto pfn = std::bind(&TestState::TestInputCallback, &testState, std::placeholders::_1);
     auto dispatch = std::make_unique<TestInteractDispatch>(pfn, &testState);
     auto inputEngine = std::make_unique<InputStateMachineEngine>(std::move(dispatch));
@@ -566,35 +561,31 @@ void InputEngineTest::RoundTripTest()
     VERIFY_IS_NOT_NULL(_stateMachine);
     testState._stateMachine = _stateMachine.get();
 
-    // Send Every VKEY through the TerminalInput module, then take the char's
-    //   from the generated INPUT_RECORDs and put them through the InputEngine.
+    // Send known round-trip capable VKEYs through the TerminalInput module, then take the chars
+    // from the generated INPUT_RECORDs and put them through the InputEngine.
     // The VKEY sequence it writes out should be the same as the original.
+    // Note: We only test VKEYs that generate VT sequences (alphanumerics and space).
+    // Testing all VKEYs fails (GH #4405) because many keys don't generate VT and won't roundtrip.
+
+    TerminalInput terminalInput;
 
-    auto pfn2 = std::bind(&TestState::RoundtripTerminalInputCallback, &testState, std::placeholders::_1);
-    TerminalInput terminalInput{ pfn2 };
+    std::vector<BYTE> testKeys;
+    testKeys.push_back(VK_SPACE);
+    for (BYTE k = '0'; k <= '9'; k++) { testKeys.push_back(k); }
+    for (BYTE k = 'A'; k <= 'Z'; k++) { testKeys.push_back(k); }
 
-    for (BYTE vkey = 0; vkey < BYTE_MAX; vkey++)
+    for (const BYTE vkey : testKeys)
     {
         wchar_t wch = (wchar_t)OneCoreSafeMapVirtualKeyW(vkey, MAPVK_VK_TO_CHAR);
-        WORD scanCode = (wchar_t)OneCoreSafeMapVirtualKeyW(vkey, MAPVK_VK_TO_VSC);
+        WORD scanCode = (WORD)OneCoreSafeMapVirtualKeyW(vkey, MAPVK_VK_TO_VSC);
 
         unsigned int uiActualKeystate = 0;
 
-        // Couple of exceptional cases here:
         if (vkey >= 'A' && vkey <= 'Z')
         {
             // A-Z need shift pressed in addition to the 'a'-'z' chars.
             uiActualKeystate = WI_SetFlag(uiActualKeystate, SHIFT_PRESSED);
         }
-        else if (vkey == VK_CANCEL || vkey == VK_PAUSE)
-        {
-            uiActualKeystate = WI_SetFlag(uiActualKeystate, LEFT_CTRL_PRESSED);
-        }
-
-        if (vkey == UNICODE_ETX)
-        {
-            testState._expectSendCtrlC = true;
-        }
 
         INPUT_RECORD irTest = { 0 };
         irTest.EventType = KEY_EVENT;
@@ -612,12 +603,13 @@ void InputEngineTest::RoundTripTest()
         testState.vExpectedInput.clear();
         testState.vExpectedInput.push_back(irTest);
 
-        auto inputKey = IInputEvent::Create(irTest);
-        terminalInput.HandleKey(inputKey.get());
+        if (const auto str = terminalInput.HandleKey(irTest))
+        {
+            testState._stateMachine->ProcessString(*str);
+        }
     }
 
     VerifyExpectedInputDrained();
-    */
 }
 
 void InputEngineTest::NonAsciiTest()