diff --git a/src/platform.h b/src/platform.h
index a56328485..104ff28d7 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -1,6 +1,8 @@
 #pragma once
 
+#ifndef _LP64
 #define _LP64 0 /* fix a warning in pdcurses 3.4 */
+#endif
 
 #ifndef UNILIB_H
 #define UNILIB_H