diff --git a/sdk/xtdk/amd64/hltypes.h b/sdk/xtdk/amd64/hltypes.h
index 51971e7..9de74be 100644
--- a/sdk/xtdk/amd64/hltypes.h
+++ b/sdk/xtdk/amd64/hltypes.h
@@ -14,6 +14,9 @@
 #include "xttypes.h"
 
 
+/* Serial port I/O addresses */
+#define COMPORT_ADDRESSES                               {0x000, 0x3F8, 0x2F8, 0x3E8, 0x2E8, 0x5F8, 0x4F8, 0x5E8, 0x4E8}
+
 /* Control Register 0 constants */
 #define CR0_PE                                          0x00000001
 #define CR0_MP                                          0x00000002
diff --git a/sdk/xtdk/i686/hltypes.h b/sdk/xtdk/i686/hltypes.h
index 8148203..3f7173b 100644
--- a/sdk/xtdk/i686/hltypes.h
+++ b/sdk/xtdk/i686/hltypes.h
@@ -14,6 +14,9 @@
 #include "xttypes.h"
 
 
+/* Serial port I/O addresses */
+#define COMPORT_ADDRESSES                               {0x000, 0x3F8, 0x2F8, 0x3E8, 0x2E8, 0x5F8, 0x4F8, 0x5E8, 0x4E8}
+
 /* Control Register 0 constants */
 #define CR0_PE                                          0x00000001
 #define CR0_MP                                          0x00000002
diff --git a/xtoskrnl/hl/cport.c b/xtoskrnl/hl/cport.c
index e12614c..685413f 100644
--- a/xtoskrnl/hl/cport.c
+++ b/xtoskrnl/hl/cport.c
@@ -9,9 +9,8 @@
 #include "xtkmapi.h"
 
 
-/* I/O port addresses for COM1 - COM8 (valid only for ia32 and amd64) */
-ULONG ComPortAddress[] = {0x000, 0x3F8, 0x2F8, 0x3E8, 0x2E8, 0x5F8, 0x4F8, 0x5E8, 0x4E8};
-
+/* COM port I/O addresses */
+ULONG ComPortAddress[] = COMPORT_ADDRESSES;
 
 /**
  * This routine gets a byte from serial port.