diff --git a/port/netxduo/inc/nx_port.h b/port/netxduo/inc/nx_port.h
index f41e642..a38389d 100644
--- a/port/netxduo/inc/nx_port.h
+++ b/port/netxduo/inc/nx_port.h
@@ -57,7 +57,11 @@
 #include "nx_user.h"
 #endif
 #include "tx_port.h"
+#if __riscv_xlen == 64
 typedef unsigned int UINT32;
+#else
+typedef unsigned long UINT32;
+#endif
 _Static_assert(sizeof(UINT32) == 4, "UINT32 must be 4 bytes");
 
 /* Default to little endian, since this is what most RISC-V targets are.  */