diff --git a/src/d3d9/d3d9_common_texture.h b/src/d3d9/d3d9_common_texture.h
index fcd9f2a0..cc27bcd2 100644
--- a/src/d3d9/d3d9_common_texture.h
+++ b/src/d3d9/d3d9_common_texture.h
@@ -47,6 +47,7 @@ namespace dxvk {
     bool                Discard;
     bool                IsBackBuffer;
     bool                IsAttachmentOnly;
+    bool                IsLockable;
   };
 
   struct D3D9ColorView {
diff --git a/src/d3d9/d3d9_device.cpp b/src/d3d9/d3d9_device.cpp
index 93da5ce3..f35dcc72 100644
--- a/src/d3d9/d3d9_device.cpp
+++ b/src/d3d9/d3d9_device.cpp
@@ -482,6 +482,12 @@ namespace dxvk {
     desc.MultisampleQuality = 0;
     desc.IsBackBuffer       = FALSE;
     desc.IsAttachmentOnly   = FALSE;
+    // Docs:
+    // Textures placed in the D3DPOOL_DEFAULT pool cannot be locked
+    // unless they are dynamic textures or they are private, FOURCC, driver formats.
+    desc.IsLockable         = Pool != D3DPOOL_DEFAULT
+                            || (Usage & D3DUSAGE_DYNAMIC)
+                            || IsVendorFormat(EnumerateFormat(Format));
 
     if (FAILED(D3D9CommonTexture::NormalizeTextureProperties(this, &desc)))
       return D3DERR_INVALIDCALL;
@@ -543,6 +549,12 @@ namespace dxvk {
     desc.MultisampleQuality = 0;
     desc.IsBackBuffer       = FALSE;
     desc.IsAttachmentOnly   = FALSE;
+    // Docs:
+    // Textures placed in the D3DPOOL_DEFAULT pool cannot be locked
+    // unless they are dynamic textures or they are private, FOURCC, driver formats.
+    desc.IsLockable         = Pool != D3DPOOL_DEFAULT
+                            || (Usage & D3DUSAGE_DYNAMIC)
+                            || IsVendorFormat(EnumerateFormat(Format));
 
     if (FAILED(D3D9CommonTexture::NormalizeTextureProperties(this, &desc)))
       return D3DERR_INVALIDCALL;
@@ -591,6 +603,12 @@ namespace dxvk {
     desc.MultisampleQuality = 0;
     desc.IsBackBuffer       = FALSE;
     desc.IsAttachmentOnly   = FALSE;
+    // Docs:
+    // Textures placed in the D3DPOOL_DEFAULT pool cannot be locked
+    // unless they are dynamic textures or they are private, FOURCC, driver formats.
+    desc.IsLockable         = Pool != D3DPOOL_DEFAULT
+                            || (Usage & D3DUSAGE_DYNAMIC)
+                            || IsVendorFormat(EnumerateFormat(Format));
 
     if (FAILED(D3D9CommonTexture::NormalizeTextureProperties(this, &desc)))
       return D3DERR_INVALIDCALL;
@@ -3539,6 +3557,7 @@ namespace dxvk {
     desc.MultisampleQuality = MultisampleQuality;
     desc.IsBackBuffer       = FALSE;
     desc.IsAttachmentOnly   = TRUE;
+    desc.IsLockable         = Lockable;
 
     if (FAILED(D3D9CommonTexture::NormalizeTextureProperties(this, &desc)))
       return D3DERR_INVALIDCALL;
@@ -3583,6 +3602,8 @@ namespace dxvk {
     desc.MultisampleQuality = 0;
     desc.IsBackBuffer       = FALSE;
     desc.IsAttachmentOnly   = Pool == D3DPOOL_DEFAULT;
+    // Docs: Off-screen plain surfaces are always lockable, regardless of their pool types.
+    desc.IsLockable         = TRUE;
 
     if (FAILED(D3D9CommonTexture::NormalizeTextureProperties(this, &desc)))
       return D3DERR_INVALIDCALL;
@@ -3632,6 +3653,8 @@ namespace dxvk {
     desc.MultisampleQuality = MultisampleQuality;
     desc.IsBackBuffer       = FALSE;
     desc.IsAttachmentOnly   = TRUE;
+    // Docs don't say anything, so just assume it's lockable.
+    desc.IsLockable         = TRUE;
 
     if (FAILED(D3D9CommonTexture::NormalizeTextureProperties(this, &desc)))
       return D3DERR_INVALIDCALL;
@@ -4243,13 +4266,7 @@ namespace dxvk {
 
     auto& desc = *(pResource->Desc());
 
-    // MSDN:
-    // Textures placed in the D3DPOOL_DEFAULT pool cannot be locked
-    // unless they are dynamic textures or they are private, FOURCC, driver formats.
-    // Also note that - unlike textures - swap chain back buffers, render targets [..] can be locked
-    if (unlikely(desc.Pool == D3DPOOL_DEFAULT
-      && !(desc.Usage & (D3DUSAGE_DYNAMIC | D3DUSAGE_RENDERTARGET | D3DUSAGE_DEPTHSTENCIL))
-      && !IsFourCCFormat(desc.Format)))
+    if (unlikely(!desc.IsLockable))
       return D3DERR_INVALIDCALL;
 
     auto& formatMapping = pResource->GetFormatMapping();
@@ -7311,6 +7328,8 @@ namespace dxvk {
       desc.MultisampleQuality = pPresentationParameters->MultiSampleQuality;
       desc.IsBackBuffer       = FALSE;
       desc.IsAttachmentOnly   = TRUE;
+      // Docs: Also note that - unlike textures - swap chain back buffers, render targets [..] can be locked
+      desc.IsLockable         = TRUE;
 
       if (FAILED(D3D9CommonTexture::NormalizeTextureProperties(this, &desc)))
         return D3DERR_NOTAVAILABLE;
diff --git a/src/d3d9/d3d9_format.h b/src/d3d9/d3d9_format.h
index b09b9d46..c38f6fe4 100644
--- a/src/d3d9/d3d9_format.h
+++ b/src/d3d9/d3d9_format.h
@@ -226,4 +226,17 @@ namespace dxvk {
     return format > D3D9Format::BINARYBUFFER;
   }
 
+  inline bool IsVendorFormat(D3D9Format format) {
+    return IsFourCCFormat(format)
+      && format != D3D9Format::MULTI2_ARGB8
+      && format != D3D9Format::UYVY
+      && format != D3D9Format::R8G8_B8G8
+      && format != D3D9Format::G8R8_G8B8
+      && format != D3D9Format::DXT1
+      && format != D3D9Format::DXT2
+      && format != D3D9Format::DXT3
+      && format != D3D9Format::DXT4
+      && format != D3D9Format::DXT5;
+  }
+
 }
diff --git a/src/d3d9/d3d9_swapchain.cpp b/src/d3d9/d3d9_swapchain.cpp
index 807740e7..e01c8041 100644
--- a/src/d3d9/d3d9_swapchain.cpp
+++ b/src/d3d9/d3d9_swapchain.cpp
@@ -897,6 +897,8 @@ namespace dxvk {
     desc.Discard            = FALSE;
     desc.IsBackBuffer       = TRUE;
     desc.IsAttachmentOnly   = FALSE;
+    // Docs: Also note that - unlike textures - swap chain back buffers, render targets [..] can be locked
+    desc.IsLockable         = TRUE;
 
     for (uint32_t i = 0; i < m_backBuffers.size(); i++)
       m_backBuffers[i] = new D3D9Surface(m_parent, &desc, this, nullptr);