diff --git a/Makefile b/Makefile
index 596a7cbca..637e8baaf 100644
--- a/Makefile
+++ b/Makefile
@@ -58,6 +58,13 @@ include mach/proto/ncg/build.mk
 
 include plat/linux/liblinux/build.mk
 
+include mach/build.mk
+include mach/i80/build.mk
+include mach/i386/build.mk
+include mach/i86/build.mk
+include mach/m68020/build.mk
+# include mach/powerpc/build.mk
+
 include plat/build.mk
 include plat/pc86/build.mk
 include plat/cpm/build.mk
diff --git a/first/core.mk b/first/core.mk
index 09b51a925..143748d98 100644
--- a/first/core.mk
+++ b/first/core.mk
@@ -31,8 +31,6 @@ endef
 
 define ackfile-rule
 $o: $s $(ACK) \
-		$(PLATIND)/descr/$(PLATFORM) \
-		$(PLATDEP)/$(PLATFORM)/as \
 		$(CCOMPILER) \
 		$(PLATFORM_$(PLATFORM)) \
 		$(EM_ENCODE)
diff --git a/mach/build.mk b/mach/build.mk
new file mode 100644
index 000000000..368e6b0ca
--- /dev/null
+++ b/mach/build.mk
@@ -0,0 +1,12 @@
+define build-architecture-impl
+	$(eval ARCHITECTURE_$(ARCH) := \
+			$(PLATDEP)/$(ARCH)/as \
+			$(PLATDEP)/$(ARCH)/ncg)
+
+	$(eval PLATFORM := $(ARCH))
+    $(call build-as)
+    $(call build-ncg)
+endef
+
+build-architecture = $(eval $(build-architecture-impl))
+
diff --git a/mach/i386/build.mk b/mach/i386/build.mk
new file mode 100644
index 000000000..f4670cc2f
--- /dev/null
+++ b/mach/i386/build.mk
@@ -0,0 +1,8 @@
+ARCH := i386
+OPTIMISATION := -O
+
+D := mach/i386
+
+$(eval $(call build-architecture))
+
+
diff --git a/mach/i80/build.mk b/mach/i80/build.mk
new file mode 100644
index 000000000..bd3cfc2b3
--- /dev/null
+++ b/mach/i80/build.mk
@@ -0,0 +1,8 @@
+ARCH := i80
+OPTIMISATION := -O
+
+D := mach/i80
+
+$(eval $(call build-architecture))
+
+
diff --git a/mach/i86/build.mk b/mach/i86/build.mk
new file mode 100644
index 000000000..2f999023d
--- /dev/null
+++ b/mach/i86/build.mk
@@ -0,0 +1,8 @@
+ARCH := i86
+OPTIMISATION := -O
+
+D := mach/i86
+
+$(eval $(call build-architecture))
+
+
diff --git a/mach/m68020/build.mk b/mach/m68020/build.mk
new file mode 100644
index 000000000..2ddaf85a0
--- /dev/null
+++ b/mach/m68020/build.mk
@@ -0,0 +1,8 @@
+ARCH := m68020
+OPTIMISATION := -O6
+
+D := mach/m68020
+
+$(eval $(call build-architecture))
+
+
diff --git a/mach/powerpc/build.mk b/mach/powerpc/build.mk
new file mode 100644
index 000000000..75cbeb5d0
--- /dev/null
+++ b/mach/powerpc/build.mk
@@ -0,0 +1,8 @@
+ARCH := powerpc
+OPTIMISATION := -O
+
+D := mach/powerpc
+
+$(eval $(call build-architecture))
+
+
diff --git a/mach/proto/as/build.mk b/mach/proto/as/build.mk
index 9404f13b9..f7b56ca66 100644
--- a/mach/proto/as/build.mk
+++ b/mach/proto/as/build.mk
@@ -2,7 +2,7 @@ define build-as-impl
     $(call reset)
 
     $(eval cflags += -Imach/$(ARCH)/as -I$(OBJDIR)/$D)
-    $(eval objdir := $(PLATFORM))
+    $(eval objdir := $(ARCH))
 
     $(call cfile, mach/proto/as/comm3.c)
     $(call dependson, $(OBJDIR)/$D/y.tab.h)
@@ -35,8 +35,8 @@ $(OBJDIR)/$D/preprocessed-comm2.y: mach/proto/as/comm2.y $(CPPANSI)
 		mach/proto/as/comm2.y > $$@
 
 	$(call file, $(LIBOBJECT))
-    $(call cprogram, $(BINDIR)/$(PLATFORM)/as)
-    $(call installto, $(PLATDEP)/$(PLATFORM)/as)
+    $(call cprogram, $(BINDIR)/$(ARCH)/as)
+    $(call installto, $(PLATDEP)/$(ARCH)/as)
 endef
 
 build-as = $(eval $(build-as-impl))
diff --git a/mach/proto/ncg/build.mk b/mach/proto/ncg/build.mk
index 100ece434..f3782322b 100644
--- a/mach/proto/ncg/build.mk
+++ b/mach/proto/ncg/build.mk
@@ -3,7 +3,7 @@ define build-ncg-impl
 $(call reset)
 
 $(eval cflags += -Imach/$(ARCH)/ncg -I$(OBJDIR)/$D -Imach/proto/ncg)
-$(eval objdir := $(PLATFORM))
+$(eval objdir := $(ARCH))
 
 $(call cfile, mach/proto/ncg/codegen.c)
 $(call cfile, mach/proto/ncg/compute.c)
@@ -37,8 +37,8 @@ $(call cfile, $(OBJDIR)/$D/tables.c)
 $(call file, $(LIBEM_DATA))
 $(call file, $(LIBFLT_ARITH))
 
-$(call cprogram, $(BINDIR)/$(PLATFORM)/ncg)
-$(call installto, $(PLATDEP)/$(PLATFORM)/ncg)
+$(call cprogram, $(BINDIR)/$(ARCH)/ncg)
+$(call installto, $(PLATDEP)/$(ARCH)/ncg)
 
 endef
 
diff --git a/plat/build.mk b/plat/build.mk
index e43b02614..3a80c438d 100644
--- a/plat/build.mk
+++ b/plat/build.mk
@@ -12,8 +12,9 @@ define build-platform-impl
 	$(call installto, $(PLATIND)/descr/$(PLATFORM))
 
 	$(eval PLATFORM_$(PLATFORM) := \
+			$(PLATIND)/descr/$(PLATFORM) \
 			$(PLATFORM_HEADERS_$(PLATFORM)) \
-			$(PLATDEP)/$(PLATFORM)/ncg)
+			$(ARCHITECTURE_$(ARCH)))
 
 	$(foreach f, $(platform-headers), $(call build-platform-headers, $f))
 
@@ -22,9 +23,6 @@ define build-platform-impl
 	$(call acklibrary, $(LIBDIR)/$(PLATFORM)/libsys.a)
 	$(call installto, $(PLATIND)/$(PLATFORM)/libsys.a)
 
-    $(call build-as)
-    $(call build-ncg)
-
     $(foreach runtime, $(RUNTIMES), $(build-runtime-$(runtime)))
 endef
 
diff --git a/plat/cpm/descr b/plat/cpm/descr
index b1b579938..436dc40cc 100644
--- a/plat/cpm/descr
+++ b/plat/cpm/descr
@@ -23,7 +23,7 @@ var C_INCLUDES=-I{EM}/share/ack/{PLATFORM}/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	program {EM}/lib/ack/{PLATFORM}/ncg
+	program {EM}/lib/ack/{ARCH}/ncg
 	args <
 	stdout
 	need .e
@@ -31,7 +31,7 @@ end
 name asopt
 	from .s
 	to .so
-	program {EM}/lib/ack/{PLATFORM}/top
+	program {EM}/lib/ack/{ARCH}/top
 	args
 	optimizer
 	stdin
@@ -40,7 +40,7 @@ end
 name as
 	from .s.so
 	to .o
-	program {EM}/lib/ack/{PLATFORM}/as
+	program {EM}/lib/ack/{ARCH}/as
 	args - -o > <
 	prep cond
 end
diff --git a/plat/linux386/descr b/plat/linux386/descr
index ff2b26dfb..a0d23ad3b 100644
--- a/plat/linux386/descr
+++ b/plat/linux386/descr
@@ -27,7 +27,7 @@ var C_INCLUDES=-I{PLATFORMDIR}/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	program {EM}/lib/ack/{PLATFORM}/ncg
+	program {EM}/lib/ack/{ARCH}/ncg
 	mapflag -gdb GF=-gdb
 	args {GF?} <
 	stdout
@@ -36,7 +36,7 @@ end
 name as
 	from .s.so
 	to .o
-	program {EM}/lib/ack/{PLATFORM}/as
+	program {EM}/lib/ack/{ARCH}/as
 	args - -o > <
 	prep cond
 end
diff --git a/plat/linux68k/descr b/plat/linux68k/descr
index 14f973d52..124955b55 100644
--- a/plat/linux68k/descr
+++ b/plat/linux68k/descr
@@ -27,7 +27,7 @@ var C_INCLUDES=-I{PLATFORMDIR}/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	program {EM}/lib/ack/{PLATFORM}/ncg
+	program {EM}/lib/ack/{ARCH}/ncg
 	mapflag -gdb GF=-gdb
 	args {GF?} <
 	stdout
@@ -36,7 +36,7 @@ end
 name as
 	from .s.so
 	to .o
-	program {EM}/lib/ack/{PLATFORM}/as
+	program {EM}/lib/ack/{ARCH}/as
 	args - -o > <
 	prep cond
 end
diff --git a/plat/linuxppc/descr b/plat/linuxppc/descr
index 2cfb9ac48..3311f24c6 100644
--- a/plat/linuxppc/descr
+++ b/plat/linuxppc/descr
@@ -27,7 +27,7 @@ var C_INCLUDES=-I{PLATFORMDIR}/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	program {EM}/lib/ack/{PLATFORM}/ncg
+	program {EM}/lib/ack/{ARCH}/ncg
 	mapflag -gdb GF=-gdb
 	args {GF?} <
 	stdout
@@ -36,7 +36,7 @@ end
 name asopt
 	from .s
 	to .so
-	program {EM}/lib/ack/{PLATFORM}/top
+	program {EM}/lib/ack/{ARCH}/top
 	args
 	optimizer
 	stdin
@@ -45,7 +45,7 @@ end
 name as
 	from .s.so
 	to .o
-	program {EM}/lib/ack/{PLATFORM}/as
+	program {EM}/lib/ack/{ARCH}/as
 	args - -o > <
 	prep cond
 end
diff --git a/plat/pc86/descr b/plat/pc86/descr
index a3f11fc4f..f02ab3eed 100644
--- a/plat/pc86/descr
+++ b/plat/pc86/descr
@@ -23,7 +23,7 @@ var C_INCLUDES=-I{PLATFORMDIR}/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	program {EM}/lib/ack/{PLATFORM}/ncg
+	program {EM}/lib/ack/{ARCH}/ncg
 	args <
 	stdout
 	need .e
@@ -31,7 +31,7 @@ end
 name as
 	from .s.so
 	to .o
-	program {EM}/lib/ack/{PLATFORM}/as
+	program {EM}/lib/ack/{ARCH}/as
 	args - -o > <
 	prep cond
 end