diff --git a/demos/demo.h b/demos/demo.h
index ab1e28f0..dc36d102 100644
--- a/demos/demo.h
+++ b/demos/demo.h
@@ -123,6 +123,21 @@ static inline void demo_blend_desc_init_default(D3D12_BLEND_DESC *desc)
     }
 }
 
+static inline HRESULT demo_create_root_signature(ID3D12Device *device,
+        const D3D12_ROOT_SIGNATURE_DESC *desc, ID3D12RootSignature **signature)
+{
+    ID3DBlob *blob;
+    HRESULT hr;
+
+    if (FAILED(hr = D3D12SerializeRootSignature(desc, D3D_ROOT_SIGNATURE_VERSION_1, &blob, NULL)))
+        return hr;
+    hr = ID3D12Device_CreateRootSignature(device, 0, ID3D10Blob_GetBufferPointer(blob),
+            ID3D10Blob_GetBufferSize(blob), &IID_ID3D12RootSignature, (void **)signature);
+    ID3D10Blob_Release(blob);
+
+    return hr;
+}
+
 #ifdef _WIN32
 #include "demo_win32.h"
 #else
diff --git a/demos/demo_win32.h b/demos/demo_win32.h
index 3cdce889..addcc953 100644
--- a/demos/demo_win32.h
+++ b/demos/demo_win32.h
@@ -325,18 +325,3 @@ static inline void demo_destroy_event(HANDLE event)
 {
     CloseHandle(event);
 }
-
-static inline HRESULT demo_create_root_signature(ID3D12Device *device,
-        const D3D12_ROOT_SIGNATURE_DESC *desc, ID3D12RootSignature **signature)
-{
-    ID3DBlob *blob;
-    HRESULT hr;
-
-    if (FAILED(hr = D3D12SerializeRootSignature(desc, D3D_ROOT_SIGNATURE_VERSION_1, &blob, NULL)))
-        return hr;
-    hr = ID3D12Device_CreateRootSignature(device, 0, ID3D10Blob_GetBufferPointer(blob),
-            ID3D10Blob_GetBufferSize(blob), &IID_ID3D12RootSignature, (void **)signature);
-    ID3D10Blob_Release(blob);
-
-    return hr;
-}
diff --git a/demos/demo_xcb.h b/demos/demo_xcb.h
index 736e8fc1..3cc2c54d 100644
--- a/demos/demo_xcb.h
+++ b/demos/demo_xcb.h
@@ -564,10 +564,3 @@ static inline void demo_destroy_event(HANDLE event)
 {
     vkd3d_destroy_event(event);
 }
-
-static inline HRESULT demo_create_root_signature(ID3D12Device *device,
-        const D3D12_ROOT_SIGNATURE_DESC *desc, ID3D12RootSignature **signature)
-{
-    return ID3D12Device_CreateRootSignature(device, 0, desc, ~(SIZE_T)0,
-            &IID_ID3D12RootSignature, (void **)signature);
-}