diff --git a/dlls/dwmapi/dwmapi.spec b/dlls/dwmapi/dwmapi.spec
index d81df3d8418..697cefc071d 100644
--- a/dlls/dwmapi/dwmapi.spec
+++ b/dlls/dwmapi/dwmapi.spec
@@ -81,7 +81,7 @@
 # @ stub DwmRenderGesture
 @ stub DwmSetDxFrameDuration
 @ stub DwmSetIconicLivePreviewBitmap
-@ stub DwmSetIconicThumbnail
+@ stdcall DwmSetIconicThumbnail(long long long)
 @ stdcall DwmSetPresentParameters(ptr ptr)
 @ stdcall DwmSetWindowAttribute(long long ptr long)
 # @ stub DwmShowContact
diff --git a/dlls/dwmapi/dwmapi_main.c b/dlls/dwmapi/dwmapi_main.c
index 8c3472a5294..7ac0b2b7900 100644
--- a/dlls/dwmapi/dwmapi_main.c
+++ b/dlls/dwmapi/dwmapi_main.c
@@ -268,3 +268,12 @@ HRESULT WINAPI DwmSetPresentParameters(HWND hwnd, DWM_PRESENT_PARAMETERS *params
     FIXME("(%p %p) stub\n", hwnd, params);
     return S_OK;
 };
+
+/**********************************************************************
+ *           DwmSetIconicThumbnail         (DWMAPI.@)
+ */
+HRESULT WINAPI DwmSetIconicThumbnail(HWND hwnd, HBITMAP hbmp, DWORD flags)
+{
+    FIXME("(%p %p %x) stub\n", hwnd, hbmp, flags);
+    return S_OK;
+};