diff --git a/sys/contrib/dev/acpica/include/actypes.h b/sys/contrib/dev/acpica/include/actypes.h
index 3e8fe6fb3558..2d71de51ede4 100644
--- a/sys/contrib/dev/acpica/include/actypes.h
+++ b/sys/contrib/dev/acpica/include/actypes.h
@@ -651,8 +651,8 @@ typedef UINT64                          ACPI_INTEGER;
 
 #define ACPI_CAST_PTR(t, p)             ((t *) (ACPI_UINTPTR_T) (p))
 #define ACPI_CAST_INDIRECT_PTR(t, p)    ((t **) (ACPI_UINTPTR_T) (p))
-#define ACPI_ADD_PTR(t, a, b)           ACPI_CAST_PTR (t, (ACPI_UINTPTR_T) (a) + (ACPI_SIZE)(b))
-#define ACPI_SUB_PTR(t, a, b)           ACPI_CAST_PTR (t, (ACPI_UINTPTR_T) (a) - (ACPI_SIZE)(b))
+#define ACPI_ADD_PTR(t, a, b)           ACPI_CAST_PTR (t, (ACPI_CAST_PTR (UINT8, (a)) + (ACPI_SIZE)(b)))
+#define ACPI_SUB_PTR(t, a, b)           ACPI_CAST_PTR (t, (ACPI_CAST_PTR (UINT8, (a)) - (ACPI_SIZE)(b)))
 #define ACPI_PTR_DIFF(a, b)             (ACPI_SIZE) (ACPI_CAST_PTR (UINT8, (a)) - ACPI_CAST_PTR (UINT8, (b)))
 
 /* Pointer/Integer type conversions */
diff --git a/usr.sbin/acpi/acpidb/Makefile b/usr.sbin/acpi/acpidb/Makefile
index a425d4014f58..493f2b897d06 100644
--- a/usr.sbin/acpi/acpidb/Makefile
+++ b/usr.sbin/acpi/acpidb/Makefile
@@ -80,3 +80,7 @@ CFLAGS+= -DACPI_EXEC_APP -fno-strict-aliasing
 LIBADD=	pthread
 
 .include <bsd.prog.mk>
+
+.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 60000
+CWARNFLAGS+=	-Wno-null-pointer-arithmetic
+.endif