diff --git a/src/wine-host/xdnd-proxy.h b/src/wine-host/xdnd-proxy.h
index de19fe31..ece5d326 100644
--- a/src/wine-host/xdnd-proxy.h
+++ b/src/wine-host/xdnd-proxy.h
@@ -14,6 +14,8 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+#pragma once
+
 #include <memory>
 
 #include <windows.h>