diff --git a/dlls/wined3d/directx.c b/dlls/wined3d/directx.c
index 29ff883331d..6617c3a8994 100644
--- a/dlls/wined3d/directx.c
+++ b/dlls/wined3d/directx.c
@@ -4000,7 +4000,6 @@ HRESULT CDECL wined3d_check_device_type(const struct wined3d *wined3d, UINT adap
         enum wined3d_device_type device_type, enum wined3d_format_id display_format,
         enum wined3d_format_id backbuffer_format, BOOL windowed)
 {
-    UINT mode_count;
     HRESULT hr;
 
     TRACE("wined3d %p, adapter_idx %u, device_type %s, display_format %s, backbuffer_format %s, windowed %#x.\n",
@@ -4014,10 +4013,7 @@ HRESULT CDECL wined3d_check_device_type(const struct wined3d *wined3d, UINT adap
      * combination is available on the given adapter. In fullscreen mode microsoft specified
      * that the display format shouldn't provide alpha and that ignoring alpha the backbuffer
      * and display format should match exactly.
-     * In windowed mode format conversion can occur and this depends on the driver. When format
-     * conversion is done, this function should nevertheless fail and applications need to use
-     * CheckDeviceFormatConversion.
-     * At the moment we assume that fullscreen and windowed have the same capabilities. */
+     * In windowed mode format conversion can occur and this depends on the driver. */
 
     /* There are only 4 display formats. */
     if (!(display_format == WINED3DFMT_B5G6R5_UNORM
@@ -4029,62 +4025,90 @@ HRESULT CDECL wined3d_check_device_type(const struct wined3d *wined3d, UINT adap
         return WINED3DERR_NOTAVAILABLE;
     }
 
-    /* If the requested display format is not available, don't continue. */
-    mode_count = wined3d_get_adapter_mode_count(wined3d, adapter_idx,
-            display_format, WINED3D_SCANLINE_ORDERING_UNKNOWN);
-    if (!mode_count)
+    if (windowed)
     {
-        TRACE("No available modes for display format %s.\n", debug_d3dformat(display_format));
-        return WINED3DERR_NOTAVAILABLE;
-    }
+        /* WINED3DFMT_B10G10R10A2_UNORM is only allowed in fullscreen mode. */
+        if (display_format == WINED3DFMT_B10G10R10A2_UNORM)
+        {
+            TRACE("Unsupported display/backbuffer format combination %s / %s for windowed mode.\n",
+                    debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
+            return WINED3DERR_NOTAVAILABLE;
+        }
 
-    /* Windowed mode allows you to specify WINED3DFMT_UNKNOWN for the backbuffer format,
-     * it means 'reuse' the display format for the backbuffer. */
-    if (!windowed && backbuffer_format == WINED3DFMT_UNKNOWN)
-    {
-        TRACE("backbuffer_format WINED3FMT_UNKNOWN only available in windowed mode.\n");
-        return WINED3DERR_NOTAVAILABLE;
-    }
+        /* Windowed mode allows you to specify WINED3DFMT_UNKNOWN for the backbuffer format,
+         * it means 'reuse' the display format for the backbuffer. */
+        if (backbuffer_format == WINED3DFMT_UNKNOWN)
+            backbuffer_format = display_format;
 
-    /* In FULLSCREEN mode WINED3DFMT_B5G6R5_UNORM can only be mixed with
-     * backbuffer format WINED3DFMT_B5G6R5_UNORM. */
-    if (display_format == WINED3DFMT_B5G6R5_UNORM && backbuffer_format != WINED3DFMT_B5G6R5_UNORM)
-    {
-        TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
-                debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
-        return WINED3DERR_NOTAVAILABLE;
+        /* In windowed mode, if color conversion from the backbuffer format to the
+         * display format is supported, then the format combination is supported. */
+        hr = wined3d_check_device_format_conversion(wined3d, adapter_idx, device_type, backbuffer_format, display_format);
+        if (FAILED(hr))
+        {
+            TRACE("Unsupported display/backbuffer format combination %s / %s; no color conversion.\n",
+                    debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
+            return WINED3DERR_NOTAVAILABLE;
+        }
     }
-
-    /* In FULLSCREEN mode WINED3DFMT_B5G5R5X1_UNORM can only be mixed with
-     * backbuffer formats WINED3DFMT_B5G5R5X1_UNORM and
-     * WINED3DFMT_B5G5R5A1_UNORM. */
-    if (display_format == WINED3DFMT_B5G5R5X1_UNORM
-            && !(backbuffer_format == WINED3DFMT_B5G5R5X1_UNORM || backbuffer_format == WINED3DFMT_B5G5R5A1_UNORM))
+    else
     {
-        TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
-                debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
-        return WINED3DERR_NOTAVAILABLE;
-    }
+        UINT mode_count;
 
-    /* In FULLSCREEN mode WINED3DFMT_B8G8R8X8_UNORM can only be mixed with
-     * backbuffer formats WINED3DFMT_B8G8R8X8_UNORM and
-     * WINED3DFMT_B8G8R8A8_UNORM. */
-    if (display_format == WINED3DFMT_B8G8R8X8_UNORM
-            && !(backbuffer_format == WINED3DFMT_B8G8R8X8_UNORM || backbuffer_format == WINED3DFMT_B8G8R8A8_UNORM))
-    {
-        TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
-                debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
-        return WINED3DERR_NOTAVAILABLE;
-    }
+        /* If the requested display format is not available, don't continue. */
+        mode_count = wined3d_get_adapter_mode_count(wined3d, adapter_idx,
+                display_format, WINED3D_SCANLINE_ORDERING_UNKNOWN);
+        if (!mode_count)
+        {
+            TRACE("No available modes for display format %s.\n", debug_d3dformat(display_format));
+            return WINED3DERR_NOTAVAILABLE;
+        }
 
-    /* WINED3DFMT_B10G10R10A2_UNORM is only allowed in fullscreen mode and it
-     * can only be mixed with backbuffer format WINED3DFMT_B10G10R10A2_UNORM. */
-    if (display_format == WINED3DFMT_B10G10R10A2_UNORM
-            && (backbuffer_format != WINED3DFMT_B10G10R10A2_UNORM || windowed))
-    {
-        TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
-                debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
-        return WINED3DERR_NOTAVAILABLE;
+        if (backbuffer_format == WINED3DFMT_UNKNOWN)
+        {
+            TRACE("backbuffer_format WINED3FMT_UNKNOWN only available in windowed mode.\n");
+            return WINED3DERR_NOTAVAILABLE;
+        }
+
+        /* In FULLSCREEN mode WINED3DFMT_B5G6R5_UNORM can only be mixed with
+         * backbuffer format WINED3DFMT_B5G6R5_UNORM. */
+        if (display_format == WINED3DFMT_B5G6R5_UNORM && backbuffer_format != WINED3DFMT_B5G6R5_UNORM)
+        {
+            TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
+                    debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
+            return WINED3DERR_NOTAVAILABLE;
+        }
+
+        /* In FULLSCREEN mode WINED3DFMT_B5G5R5X1_UNORM can only be mixed with
+         * backbuffer formats WINED3DFMT_B5G5R5X1_UNORM and
+         * WINED3DFMT_B5G5R5A1_UNORM. */
+        if (display_format == WINED3DFMT_B5G5R5X1_UNORM
+                && !(backbuffer_format == WINED3DFMT_B5G5R5X1_UNORM || backbuffer_format == WINED3DFMT_B5G5R5A1_UNORM))
+        {
+            TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
+                    debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
+            return WINED3DERR_NOTAVAILABLE;
+        }
+
+        /* In FULLSCREEN mode WINED3DFMT_B8G8R8X8_UNORM can only be mixed with
+         * backbuffer formats WINED3DFMT_B8G8R8X8_UNORM and
+         * WINED3DFMT_B8G8R8A8_UNORM. */
+        if (display_format == WINED3DFMT_B8G8R8X8_UNORM
+                && !(backbuffer_format == WINED3DFMT_B8G8R8X8_UNORM || backbuffer_format == WINED3DFMT_B8G8R8A8_UNORM))
+        {
+            TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
+                    debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
+            return WINED3DERR_NOTAVAILABLE;
+        }
+
+        /* WINED3DFMT_B10G10R10A2_UNORM can only be mixed with backbuffer format
+         * WINED3DFMT_B10G10R10A2_UNORM. */
+        if (display_format == WINED3DFMT_B10G10R10A2_UNORM
+                && backbuffer_format != WINED3DFMT_B10G10R10A2_UNORM)
+        {
+            TRACE("Unsupported display/backbuffer format combination %s / %s.\n",
+                    debug_d3dformat(display_format), debug_d3dformat(backbuffer_format));
+            return WINED3DERR_NOTAVAILABLE;
+        }
     }
 
     /* Use CheckDeviceFormat to see if the backbuffer_format is usable with the given display_format */