diff --git a/sdk/xtdk/amd64/hlfuncs.h b/sdk/xtdk/amd64/hlfuncs.h
index 531c202..80f2c0b 100644
--- a/sdk/xtdk/amd64/hlfuncs.h
+++ b/sdk/xtdk/amd64/hlfuncs.h
@@ -15,9 +15,6 @@
 #include <amd64/xtstruct.h>
 
 
-/* I/O port addresses for COM ports */
-extern ULONG ComPortAddress[];
-
 /* HAL library routines forward references */
 XTCDECL
 VOID
diff --git a/sdk/xtdk/hlfuncs.h b/sdk/xtdk/hlfuncs.h
index 55ce2ff..3ee35d9 100644
--- a/sdk/xtdk/hlfuncs.h
+++ b/sdk/xtdk/hlfuncs.h
@@ -14,9 +14,6 @@
 #include <xttypes.h>
 
 
-/* I/O port addresses for COM ports */
-extern ULONG ComPortAddress[];
-
 /* HAL library routines forward references */
 XTCDECL
 XTSTATUS
diff --git a/sdk/xtdk/i686/hlfuncs.h b/sdk/xtdk/i686/hlfuncs.h
index 0f905ae..0f35c75 100644
--- a/sdk/xtdk/i686/hlfuncs.h
+++ b/sdk/xtdk/i686/hlfuncs.h
@@ -15,9 +15,6 @@
 #include <i686/xtstruct.h>
 
 
-/* I/O port addresses for COM ports */
-extern ULONG ComPortAddress[];
-
 /* HAL library routines forward references */
 XTCDECL
 VOID