diff --git a/src/TeamsISO.Engine.NdiInterop/NdiNative.cs b/src/TeamsISO.Engine.NdiInterop/NdiNative.cs
index f4a47fd..a3d66b2 100644
--- a/src/TeamsISO.Engine.NdiInterop/NdiNative.cs
+++ b/src/TeamsISO.Engine.NdiInterop/NdiNative.cs
@@ -4,13 +4,30 @@ namespace TeamsISO.Engine.NdiInterop;
 
 /// <summary>
 /// P/Invoke declarations for the NewTek/Vizrt NDI SDK 6 native library.
-/// On Windows the import target is <c>Processing.NDI.Lib.x64.dll</c>; the loader resolves it
-/// from the NDI Runtime installation path or from the application directory.
+/// On Windows the import target is <c>Processing.NDI.Lib.x64.dll</c>. Resolution of
+/// the DLL is handled by <see cref="NdiNativeLibraryResolver"/>, which loads it from
+/// the NDI Runtime installation directory exposed by the
+/// <c>NDI_RUNTIME_DIR_V&lt;n&gt;</c> environment variables — the NDI installer sets
+/// these but does not always add the runtime directory to <c>PATH</c>, so a default
+/// loader-based resolution would fail with <c>0x8007007E</c> on otherwise correctly
+/// installed machines.
 /// </summary>
 internal static class NdiNative
 {
     private const string LibName = "Processing.NDI.Lib.x64";
 
+    /// <summary>
+    /// Registers <see cref="NdiNativeLibraryResolver"/> with the runtime before any
+    /// P/Invoke against <see cref="LibName"/> fires. The static constructor is
+    /// guaranteed to run before the first access to any member of this type, which
+    /// includes the very first <c>[DllImport]</c> call site, so the resolver is
+    /// always in place when the loader needs it.
+    /// </summary>
+    static NdiNative()
+    {
+        NdiNativeLibraryResolver.Register();
+    }
+
     // ---- Lifecycle ----
     [DllImport(LibName, EntryPoint = "NDIlib_initialize", CallingConvention = CallingConvention.Cdecl)]
     [return: MarshalAs(UnmanagedType.U1)]
diff --git a/src/TeamsISO.Engine.NdiInterop/NdiNativeLibraryResolver.cs b/src/TeamsISO.Engine.NdiInterop/NdiNativeLibraryResolver.cs
new file mode 100644
index 0000000..26ada5c
--- /dev/null
+++ b/src/TeamsISO.Engine.NdiInterop/NdiNativeLibraryResolver.cs
@@ -0,0 +1,66 @@
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+namespace TeamsISO.Engine.NdiInterop;
+
+/// <summary>
+/// Resolves the NDI native library (<c>Processing.NDI.Lib.x64.dll</c>) from the
+/// NDI Runtime install directory exposed via <c>NDI_RUNTIME_DIR_V&lt;n&gt;</c>
+/// environment variables.
+///
+/// The NDI installer creates these env vars but does not always add the runtime
+/// directory to <c>PATH</c>, so a default <c>[DllImport("Processing.NDI.Lib.x64")]</c>
+/// can fail with <c>0x8007007E</c> ("the specified module could not be found") on
+/// otherwise correctly installed machines. This resolver patches that gap by
+/// pre-loading the DLL from the install dir before the runtime falls back to its
+/// default search algorithm.
+///
+/// The resolver is registered from the static constructor of <see cref="NdiNative"/>,
+/// which guarantees it runs before the first P/Invoke on that type fires. On
+/// non-Windows the resolver short-circuits; the assembly's P/Invokes are gated by
+/// <c>[SupportedOSPlatform("windows")]</c> and won't fire there in any case.
+/// </summary>
+internal static class NdiNativeLibraryResolver
+{
+    private const string NdiX64LibraryName = "Processing.NDI.Lib.x64";
+    private const string NdiX64LibraryFile = "Processing.NDI.Lib.x64.dll";
+
+    /// <summary>
+    /// NDI runtime install-dir environment variables, in preference order.
+    /// V6 is what TeamsISO is built against; V5/V4 are listed as graceful fallbacks
+    /// for installs that pre-date V6 — the runtime probe will still report a
+    /// version mismatch, but at least the DLL will load and the engine can surface
+    /// a clear alert instead of dying with DllNotFoundException.
+    /// </summary>
+    private static readonly string[] EnvVarFallbacks =
+    {
+        "NDI_RUNTIME_DIR_V6",
+        "NDI_RUNTIME_DIR_V5",
+        "NDI_RUNTIME_DIR_V4",
+    };
+
+    internal static void Register()
+    {
+        NativeLibrary.SetDllImportResolver(typeof(NdiNativeLibraryResolver).Assembly, Resolve);
+    }
+
+    private static IntPtr Resolve(string libraryName, Assembly assembly, DllImportSearchPath? searchPath)
+    {
+        if (libraryName != NdiX64LibraryName) return IntPtr.Zero;
+        if (!OperatingSystem.IsWindows()) return IntPtr.Zero;
+
+        foreach (var envVar in EnvVarFallbacks)
+        {
+            var dir = Environment.GetEnvironmentVariable(envVar);
+            if (string.IsNullOrEmpty(dir)) continue;
+            var path = Path.Combine(dir, NdiX64LibraryFile);
+            if (!File.Exists(path)) continue;
+            if (NativeLibrary.TryLoad(path, out var handle))
+                return handle;
+        }
+
+        // Fall through to default loader (PATH, app dir, etc.) — preserves the
+        // chance that someone added the NDI dir to PATH manually.
+        return IntPtr.Zero;
+    }
+}