diff --git a/src/microsoft/vulkan/dzn_private.h b/src/microsoft/vulkan/dzn_private.h
index 1c9ad862899..e7e0ee57b0a 100644
--- a/src/microsoft/vulkan/dzn_private.h
+++ b/src/microsoft/vulkan/dzn_private.h
@@ -216,7 +216,7 @@ void
 d3d12_enable_gpu_validation();
 
 ID3D12Device1 *
-d3d12_create_device(IUnknown *adapter, bool experimental_features);
+d3d12_create_device(IDXGIAdapter1 *adapter, bool experimental_features);
 
 struct dzn_queue {
    struct vk_queue vk;
diff --git a/src/microsoft/vulkan/dzn_util.cpp b/src/microsoft/vulkan/dzn_util.cpp
index ce428984f62..9f0924f238d 100644
--- a/src/microsoft/vulkan/dzn_util.cpp
+++ b/src/microsoft/vulkan/dzn_util.cpp
@@ -119,7 +119,7 @@ d3d12_enable_gpu_validation()
 }
 
 ID3D12Device1 *
-d3d12_create_device(IUnknown *adapter, bool experimental_features)
+d3d12_create_device(IDXGIAdapter1 *adapter, bool experimental_features)
 {
    typedef HRESULT(WINAPI *PFN_D3D12CREATEDEVICE)(IUnknown*, D3D_FEATURE_LEVEL, REFIID, void**);
    PFN_D3D12CREATEDEVICE D3D12CreateDevice;