diff --git a/sys/dev/acpica/Osd/OsdHardware.c b/sys/dev/acpica/Osd/OsdHardware.c
index 5c38cbf2649..46deb96863f 100644
--- a/sys/dev/acpica/Osd/OsdHardware.c
+++ b/sys/dev/acpica/Osd/OsdHardware.c
@@ -36,7 +36,11 @@
 #include <machine/bus_pio.h>
 #include <machine/bus.h>
 #include <machine/pci_cfgreg.h>
+#if __FreeBSD_version >= 500000
 #include <dev/pci/pcireg.h>
+#else
+#include <pci/pcireg.h>
+#endif
 
 /*
  * ACPICA's rather gung-ho approach to hardware resource ownership is a little
diff --git a/sys/dev/acpica/acpivar.h b/sys/dev/acpica/acpivar.h
index 12a5a687b14..cd254ac8c28 100644
--- a/sys/dev/acpica/acpivar.h
+++ b/sys/dev/acpica/acpivar.h
@@ -39,6 +39,10 @@
 #include <machine/bus.h>
 #include <machine/resource.h>
 
+#if __FreeBSD_version < 500000
+typedef vm_offset_t vm_paddr_t;
+#endif
+
 struct acpi_softc {
     device_t		acpi_dev;
     dev_t		acpi_dev_t;
@@ -389,12 +393,14 @@ extern int	acpi_cmbat_get_battinfo(int, struct acpi_battinfo *);
 
 extern int	acpi_acad_get_acline(int *);
 
+#if __FreeBSD_version >= 500000
 #ifndef ACPI_MAX_THREADS
 #define ACPI_MAX_THREADS	3
 #endif
 #if ACPI_MAX_THREADS > 0
 #define ACPI_USE_THREADS
 #endif
+#endif
 
 #ifdef ACPI_USE_THREADS
 /*
diff --git a/sys/i386/acpica/acpi_machdep.c b/sys/i386/acpica/acpi_machdep.c
index 6d48588e1c9..ebe2d9b9156 100644
--- a/sys/i386/acpica/acpi_machdep.c
+++ b/sys/i386/acpica/acpi_machdep.c
@@ -52,7 +52,11 @@ static device_t	acpi_dev;
 #include <machine/apm_bios.h>
 #include <machine/pc/bios.h>
 
+#if __FreeBSD_version < 500000
+#include <i386/apm/apm.h>
+#else
 #include <i386/bios/apm.h>
+#endif
 
 static struct apm_softc	apm_softc;
 
diff --git a/sys/i386/acpica/acpi_wakeup.c b/sys/i386/acpica/acpi_wakeup.c
index 9f02e9358fb..642eb1007c1 100644
--- a/sys/i386/acpica/acpi_wakeup.c
+++ b/sys/i386/acpica/acpi_wakeup.c
@@ -58,6 +58,11 @@
 
 #include "acpi_wakecode.h"
 
+#if __FreeBSD_version < 500000
+#define	vm_page_lock_queues()
+#define	vm_page_unlock_queues()
+#endif
+
 extern void initializecpu(void);
 
 static struct region_descriptor	r_idt, r_gdt, *p_gdt;