diff --git a/src/system/SYSTEM.h b/src/system/SYSTEM.h
index 75a0aa52..0dc539b7 100644
--- a/src/system/SYSTEM.h
+++ b/src/system/SYSTEM.h
@@ -27,6 +27,10 @@ typedef unsigned char        SYSTEM_CARD8;
 #endif
 
 
+// For FreeBSD and OpenBSD:
+typedef SYSTEM_ADDRESS size_t
+#define _SIZE_T_DECLARED
+
 void *memcpy(void *dest, const void *source, SYSTEM_ADDRESS size);