diff --git a/headers/config/HaikuConfig.h b/headers/config/HaikuConfig.h
index ca25ae720b..c1dea0dae2 100644
--- a/headers/config/HaikuConfig.h
+++ b/headers/config/HaikuConfig.h
@@ -36,6 +36,7 @@
 #	define __HAIKU_ARCH					ppc
 #	define __HAIKU_ARCH_ABI				"ppc"
 #	define __HAIKU_ARCH_PPC				1
+#	define __HAIKU_ARCH_PHYSICAL_BITS	64
 #	define __HAIKU_BIG_ENDIAN			1
 #elif __M68K__
 #	define __HAIKU_ARCH					m68k