diff --git a/windows/winhelp.c b/windows/winhelp.c
index 8b652c7b..64f6ad45 100644
--- a/windows/winhelp.c
+++ b/windows/winhelp.c
@@ -105,7 +105,7 @@ void launch_help(HWND hwnd, const char *topic)
 #endif /* NO_HTMLHELP */
 	if (help_path) {
 	    char *cmd = dupprintf("JI(`',`%.*s')", colonpos, topic);
-	    WinHelp(hwnd, help_path, HELP_COMMAND, (DWORD)cmd);
+	    WinHelp(hwnd, help_path, HELP_COMMAND, (ULONG_PTR)cmd);
 	    sfree(cmd);
 	}
     } else {