diff --git a/Directory.Build.props b/Directory.Build.props
index 932802e19..ffecef5ab 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -53,4 +53,14 @@
       <CETCompat>false</CETCompat>
     </Link>
   </ItemDefinitionGroup>
+
+  <!-- Suppress LNK4279 for ARM64EC: the new MSVC toolset (14.51+) classifies POINT as an
+       integer (i8) icall thunk while pre-built MFC libs use a struct (m8) thunk.
+       Both thunks produce equivalent code for this trivially-copyable 8-byte struct,
+       so the mismatch is a diagnostic false-positive introduced by the ABI transition. -->
+  <ItemDefinitionGroup Condition="'$(Platform)' == 'ARM64EC'">
+    <Link>
+      <AdditionalOptions>/IGNORE:4279 %(AdditionalOptions)</AdditionalOptions>
+    </Link>
+  </ItemDefinitionGroup>
 </Project>
diff --git a/UI/Dialogs/Dialog.cpp b/UI/Dialogs/Dialog.cpp
index 3d8c0470c..4c5a3a9c2 100644
--- a/UI/Dialogs/Dialog.cpp
+++ b/UI/Dialogs/Dialog.cpp
@@ -114,9 +114,14 @@ namespace dialog
 			rcCloseIcon.top,
 			rcCloseIcon.right,
 			rcCloseIcon.bottom);
-		if (PtInRect(&rcCloseIcon, pt)) ret = HTCLOSE;
-		if (PtInRect(&rcMaxIcon, pt)) ret = HTMAXBUTTON;
-		if (PtInRect(&rcMinIcon, pt)) ret = HTMINBUTTON;
+		// Inline point-in-rect check to avoid ARM64EC icall thunk mismatch (LNK4279)
+		// between our code and the pre-built MFC library for PtInRect(RECT*, POINT).
+		const auto ptInRect = [](const RECT& rc, POINT p) noexcept {
+			return p.x >= rc.left && p.x < rc.right && p.y >= rc.top && p.y < rc.bottom;
+		};
+		if (ptInRect(rcCloseIcon, pt)) ret = HTCLOSE;
+		if (ptInRect(rcMaxIcon, pt)) ret = HTMAXBUTTON;
+		if (ptInRect(rcMinIcon, pt)) ret = HTMINBUTTON;
 
 		output::DebugPrint(output::dbgLevel::UI, L"CheckButtons result: %ws\r\n", FormatHT(ret).c_str());