diff --git a/Makefile b/Makefile
index 28641a9..d326c7d 100644
--- a/Makefile
+++ b/Makefile
@@ -241,79 +241,79 @@ $(GEN):
 
 $(GEN)/posix_boot.h: posix/posix_boot.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name boot --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name boot --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/posix_boot.h.dd
 
 $(GEN)/windows_boot_extra.h: windows/windows_boot_extra.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name boot_extra --header win --depsout $@.dd \
+    -I . -I $(OUT) --name boot_extra --header win --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/windows_boot_extra.h.dd
 
 $(GEN)/windows_boot.h: windows/windows_boot.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name boot --header win --depsout $@.dd \
+    -I . -I $(OUT) --name boot --header win --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/windows_boot.h.dd
 
 $(GEN)/pico_ice_boot.h: pico-ice/pico_ice_boot.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name boot --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name boot --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/pico_ice_boot.h.dd
 
 $(GEN)/esp32_boot.h: esp32/esp32_boot.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name boot --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name boot --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_boot.h.dd
 
 $(GEN)/esp32_assembler.h: common/assembler.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name assembler_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name assembler_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_assembler.h.dd
 
 $(GEN)/esp32_xtensa-assembler.h: esp32/optional/assemblers/xtensa-assembler.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name xtensa_assembler_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name xtensa_assembler_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_xtensa-assembler.h.dd
 
 $(GEN)/esp32_riscv-assembler.h: esp32/optional/assemblers/riscv-assembler.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name riscv_assembler_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name riscv_assembler_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_riscv-assembler.h.dd
 
 $(GEN)/esp32_camera.h: esp32/optional/camera/camera_server.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name camera_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name camera_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_camera.h.dd
 
 $(GEN)/esp32_interrupts.h: esp32/optional/interrupts/timers.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name interrupts_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name interrupts_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_interrupts.h.dd
 
 $(GEN)/esp32_oled.h: esp32/optional/oled/oled.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name oled_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name oled_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_oled.h.dd
 
 $(GEN)/esp32_spi-flash.h: esp32/optional/spi-flash/spi-flash.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name spi_flash_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name spi_flash_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_spi-flash.h.dd
 
 $(GEN)/esp32_serial-bluetooth.h: esp32/optional/serial-bluetooth/serial-bluetooth.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name serial_bluetooth_source --header cpp --depsout $@.dd \
+    -I . -I $(OUT) --name serial_bluetooth_source --header cpp --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_serial-bluetooth.h.dd
 
@@ -349,7 +349,7 @@ $(GEN)/web_sys.js: $(GEN)/dump_web_opcodes | $(GEN)
 
 $(GEN)/web_boot.js: web/web_boot.fs | $(GEN)
 	./tools/importation.py -i $< -o $@ \
-    -I . -I $(GEN) --name boot --header web --depsout $@.dd \
+    -I . -I $(OUT) --name boot --header web --depsout $@.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/web_boot.js.dd
 
@@ -450,7 +450,7 @@ $(WINDOWS)/uEf32.obj: \
     windows/main.c \
     $(GEN)/windows_boot_extra.h \
     $(GEN)/windows_boot.h | $(WINDOWS)
-	./tools/importation.py -i $< -o $@ --no-out -I . -I $(GEN) --depsout $@.dd
+	./tools/importation.py -i $< -o $@ --no-out -I . -I $(OUT) --depsout $@.dd
 	$(CL32) /c /Fo$@ $(WIN_CFLAGS) $<
 -include $(WINDOWS)/uEf32.obj.dd
 
@@ -463,7 +463,7 @@ $(WINDOWS)/uEf64.obj: \
     windows/main.c \
     $(GEN)/windows_boot_extra.h \
     $(GEN)/windows_boot.h | $(WINDOWS)
-	./tools/importation.py -i $< -o $@ --no-out -I . -I $(GEN) --depsout $@.dd
+	./tools/importation.py -i $< -o $@ --no-out -I . -I $(OUT) --depsout $@.dd
 	$(CL64) /c /Fo$@ $(WIN_CFLAGS) $<
 -include $(WINDOWS)/uEf64.obj.dd
 
@@ -511,7 +511,7 @@ $(ESP32)/ESP32forth/ESP32forth.ino: \
     $(GEN)/esp32_boot.h | $(ESP32)/ESP32forth
 	./tools/importation.py -i $< -o $@ \
     --keep-first-comment \
-    -I . -I $(GEN) --depsout $(GEN)/esp32.dd \
+    -I . -I $(OUT) --depsout $(GEN)/esp32.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32.dd
 
@@ -531,7 +531,7 @@ $(ESP32)/ESP32forth/optional/assemblers.h: \
     $(GEN)/esp32_riscv-assembler.h | $(ESP32)/ESP32forth/optional
 	./tools/importation.py -i $< -o $@ \
     --keep-first-comment \
-    -I . -I $(GEN) --depsout $(GEN)/esp32_optional_assemblers.h.dd \
+    -I . -I $(OUT) --depsout $(GEN)/esp32_optional_assemblers.h.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_optional_assemblers.h.dd
 
@@ -540,7 +540,7 @@ $(ESP32)/ESP32forth/optional/camera.h: \
     $(GEN)/esp32_camera.h | $(ESP32)/ESP32forth/optional
 	./tools/importation.py -i $< -o $@ \
     --keep-first-comment \
-    -I . -I $(GEN) --depsout $(GEN)/esp32_optional_camera.h.dd \
+    -I . -I $(OUT) --depsout $(GEN)/esp32_optional_camera.h.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_optional_camera.h.dd
 
@@ -549,7 +549,7 @@ $(ESP32)/ESP32forth/optional/interrupts.h: \
     $(GEN)/esp32_interrupts.h | $(ESP32)/ESP32forth/optional
 	./tools/importation.py -i $< -o $@ \
     --keep-first-comment \
-    -I . -I $(GEN) --depsout $(GEN)/esp32_optional_interrupts.h.dd \
+    -I . -I $(OUT) --depsout $(GEN)/esp32_optional_interrupts.h.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_optional_interrupts.h.dd
 
@@ -558,7 +558,7 @@ $(ESP32)/ESP32forth/optional/oled.h: \
     $(GEN)/esp32_oled.h | $(ESP32)/ESP32forth/optional
 	./tools/importation.py -i $< -o $@ \
     --keep-first-comment \
-    -I . -I $(GEN) --depsout $(GEN)/esp32_optional_oled.h.dd \
+    -I . -I $(OUT) --depsout $(GEN)/esp32_optional_oled.h.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_optional_oled.h.dd
 
@@ -573,7 +573,7 @@ $(ESP32)/ESP32forth/optional/serial-bluetooth.h: \
     $(GEN)/esp32_serial-bluetooth.h | $(ESP32)/ESP32forth/optional
 	./tools/importation.py -i $< -o $@ \
     --keep-first-comment \
-    -I . -I $(GEN) --depsout $(GEN)/esp32_optional_serial-bluetooth.h.dd \
+    -I . -I $(OUT) --depsout $(GEN)/esp32_optional_serial-bluetooth.h.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_optional_serial-bluetooth.h.dd
 
@@ -582,7 +582,7 @@ $(ESP32)/ESP32forth/optional/spi-flash.h: \
     $(GEN)/esp32_spi-flash.h | $(ESP32)/ESP32forth/optional
 	./tools/importation.py -i $< -o $@ \
     --keep-first-comment \
-    -I . -I $(GEN) --depsout $(GEN)/esp32_optional_spi-flash.h.dd \
+    -I . -I $(OUT) --depsout $(GEN)/esp32_optional_spi-flash.h.dd \
     -DVERSION=$(VERSION) -DREVISION=$(REVISION)
 -include $(GEN)/esp32_optional_spi-flash.h.dd
 
diff --git a/esp32/optional/assemblers/assemblers.h b/esp32/optional/assemblers/assemblers.h
index 4cd68b6..28c94a9 100644
--- a/esp32/optional/assemblers/assemblers.h
+++ b/esp32/optional/assemblers/assemblers.h
@@ -24,7 +24,7 @@
       PUSH assembler_source; PUSH sizeof(assembler_source) - 1) \
   PLATFORM_ASSEMBLER_SUPPORT
 
-#include "esp32_assembler.h"
+#include "gen/esp32_assembler.h"
 
 #if defined(__riscv)
 
@@ -32,7 +32,7 @@
    XV(internals, "riscv-assembler-source", RISCV_ASSEMBLER_SOURCE, \
        PUSH riscv_assembler_source; PUSH sizeof(riscv_assembler_source) - 1)
 
-#include "esp32_riscv-assembler.h"
+#include "gen/esp32_riscv-assembler.h"
 
 #else
 
@@ -40,6 +40,6 @@
    XV(internals, "xtensa-assembler-source", XTENSA_ASSEMBLER_SOURCE, \
        PUSH xtensa_assembler_source; PUSH sizeof(xtensa_assembler_source) - 1)
 
-#include "esp32_xtensa-assembler.h"
+#include "gen/esp32_xtensa-assembler.h"
 
 #endif
diff --git a/esp32/optional/camera/camera.h b/esp32/optional/camera/camera.h
index 477c399..f920ae2 100644
--- a/esp32/optional/camera/camera.h
+++ b/esp32/optional/camera/camera.h
@@ -31,4 +31,4 @@
   YV(camera, esp_camera_save_to_nvs, n0 = esp_camera_save_to_nvs(c0)) \
   YV(camera, esp_camera_load_from_nvs, n0 = esp_camera_load_from_nvs(c0))
 
-#include "esp32_camera.h"
+#include "gen/esp32_camera.h"
diff --git a/esp32/optional/interrupts/interrupts.h b/esp32/optional/interrupts/interrupts.h
index fa75649..04c6b6c 100644
--- a/esp32/optional/interrupts/interrupts.h
+++ b/esp32/optional/interrupts/interrupts.h
@@ -154,4 +154,4 @@ static cell_t TimerIsrCallbackAdd(cell_t group, cell_t timer, cell_t xt, cell_t
   return timer_isr_callback_add((timer_group_t) group, (timer_idx_t) timer, HandleInterruptAndRet, args, flags);
 }
 
-#include "esp32_interrupts.h"
+#include "gen/esp32_interrupts.h"
diff --git a/esp32/optional/oled/oled.h b/esp32/optional/oled/oled.h
index 785e6da..92e0a07 100644
--- a/esp32/optional/oled/oled.h
+++ b/esp32/optional/oled/oled.h
@@ -55,4 +55,4 @@ static Adafruit_SSD1306 *oled_display = 0;
   YV(oled, OledRectR, oled_display->drawRoundRect(n5, n4, n3, n2, n1, n0); DROPn(5)) \
   YV(oled, OledRectRF, oled_display->fillRoundRect(n5, n4, n3, n2, n1, n0 ); DROPn(5))
 
-#include "esp32_oled.h"
+#include "gen/esp32_oled.h"
diff --git a/esp32/optional/serial-bluetooth/serial-bluetooth.h b/esp32/optional/serial-bluetooth/serial-bluetooth.h
index b9638c7..45ee380 100644
--- a/esp32/optional/serial-bluetooth/serial-bluetooth.h
+++ b/esp32/optional/serial-bluetooth/serial-bluetooth.h
@@ -47,4 +47,4 @@
   /* Bluetooth */ \
   YV(bluetooth, esp_bt_dev_get_address, PUSH esp_bt_dev_get_address())
 
-#include "esp32_serial-bluetooth.h"
+#include "gen/esp32_serial-bluetooth.h"
diff --git a/esp32/optional/spi-flash/spi-flash.h b/esp32/optional/spi-flash/spi-flash.h
index 9204337..1238114 100644
--- a/esp32/optional/spi-flash/spi-flash.h
+++ b/esp32/optional/spi-flash/spi-flash.h
@@ -77,4 +77,4 @@
       n0 = esp_partition_check_identity((const esp_partition_t *) a1, \
                                         (const esp_partition_t *) a0); NIP)
 
-#include "esp32_spi-flash.h"
+#include "gen/esp32_spi-flash.h"
diff --git a/tools/configure.py b/tools/configure.py
index 0710df0..46777bc 100755
--- a/tools/configure.py
+++ b/tools/configure.py
@@ -27,8 +27,8 @@ REVISION = 'TODO'
 
 CFLAGS_COMMON = [
   '-O2',
-  '-I', './',
   '-I', '$src',
+  '-I', './',
 ]
 
 CFLAGS_MINIMIZE = [
@@ -98,7 +98,7 @@ rule mkdir
 rule importation
   description = importation
   depfile = $out.dd
-  command = ../tools/importation.py -i $in -o $out -I . -I $src $options --depsout $depfile -DVERSION=$version -DREVSION=$revision
+  command = ../tools/importation.py -i $in -o $out -I . -I $src $options --depsout $depfile -DVERSION=$version -DREVISION=$revision
 
 build gen: mkdir
 build posix: mkdir
@@ -130,61 +130,32 @@ def Importation(target, source, header_mode='cpp', name=None, keep=False, deps=N
   if deps:
     output += f'  depfile = {deps}\n'
 
-def Esp32Optional(target, c_source, header, name, forth_source):
-  Importation(target, name, forth_source)
-  Importation('gen/' + header, name, forth_source)
+def Esp32Optional(main_name, main_source, parts):
+  for name, source in parts:
+    Importation('gen/esp32_' + name + '.h',
+                source, name=name.replace('-', '_') + '_source')
+  if not main_source:
+    main_source = 'gen/esp32_' + main_name + '.h'
+  Importation('esp32/ESP32forth/optional/' + main_name + '.h',
+              main_source,
+            keep=True,
+            deps='gen/esp32_optional_' + main_name + '.h.dd',
+            implicit=['gen/esp32_' + i + '.h' for i, _ in parts])
 
-Importation('gen/esp32_assembler.h',
-            '$src/common/assembler.fs', name='assembler_source')
-Importation('gen/esp32_xtensa-assembler.h',
-            '$src/esp32/optional/assemblers/xtensa-assembler.fs', name='xtensa_assembler_source')
-Importation('gen/esp32_riscv-assembler.h',
-            '$src/esp32/optional/assemblers/riscv-assembler.fs', name='riscv_assembler_source')
-Importation('esp32/ESP32forth/optional/assemblers.h',
-            '$src/esp32/optional/assemblers/assemblers.h',
-            deps='gen/esp32_optional_assemblers.h.dd',
-            implicit=[
-              'gen/esp32_assembler.h',
-              'gen/esp32_xtensa-assembler.h',
-              'gen/esp32_riscv-assembler.h',
-            ])
-
-Importation('gen/esp32_camera.h',
-            '$src/esp32/optional/camera/camera_server.fs', name='camera_source')
-Importation('esp32/ESP32forth/optional/camera.h',
-            'gen/esp32_camera.h',
-            deps='gen/esp32_optional_camera.h.dd',
-            implicit=['gen/esp32_camera.h'])
-
-Importation('gen/esp32_interrupts.h',
-            '$src/esp32/optional/interrupts/timers.fs', name='interrupts_source')
-Importation('esp32/ESP32forth/optional/interrupts.h',
-            'gen/esp32_interrupts.h',
-            deps='gen/esp32_optional_interrupts.h.dd',
-            implicit=['gen/esp32_interrupts.h'])
-
-Importation('gen/esp32_oled.h',
-            '$src/esp32/optional/oled/oled.fs', name='oled_source')
-Importation('esp32/ESP32forth/optional/oled.h',
-            'gen/esp32_oled.h',
-            deps='gen/esp32_optional_oled.h.dd',
-            implicit=['gen/esp32_oled.h'])
-
-Importation('gen/esp32_spi-flash.h',
-            '$src/esp32/optional/spi-flash/spi-flash.fs',
-            name='spi_flash_source')
-Importation('esp32/ESP32forth/optional/spi-flash.h',
-            'gen/esp32_spi-flash.h',
-            deps='gen/esp32_optional_spi-flash.h.dd',
-            implicit=['gen/esp32_spi-flash.h'])
-
-Importation('gen/esp32_serial-bluetooth.h',
-            '$src/esp32/optional/serial-bluetooth/serial-bluetooth.fs',
-            name='serial_bluetooth_source')
-Importation('esp32/ESP32forth/optional/serial-bluetooth.h',
-            'gen/esp32_serial-bluetooth.h',
-            deps='gen/esp32_optional_serial-bluetooth.h.dd',
-            implicit=['gen/esp32_serial-bluetooth.h'])
+Esp32Optional('assemblers', '$src/esp32/optional/assemblers/assemblers.h',
+              [('assembler', '$src/common/assembler.fs'),
+               ('xtensa-assembler', '$src/esp32/optional/assemblers/xtensa-assembler.fs'),
+               ('riscv-assembler', '$src/esp32/optional/assemblers/riscv-assembler.fs')])
+Esp32Optional('camera', '$src/esp32/optional/camera/camera.h',
+              [('camera', '$src/esp32/optional/camera/camera_server.fs')])
+Esp32Optional('interrupts', '$src/esp32/optional/interrupts/interrupts.h',
+              [('interrupts', '$src/esp32/optional/interrupts/timers.fs')])
+Esp32Optional('oled', '$src/esp32/optional/oled/oled.h',
+              [('oled', '$src/esp32/optional/oled/oled.fs')])
+Esp32Optional('spi-flash', '$src/esp32/optional/spi-flash/spi-flash.h',
+              [('spi-flash', '$src/esp32/optional/spi-flash/spi-flash.fs')])
+Esp32Optional('serial-bluetooth', '$src/esp32/optional/serial-bluetooth/serial-bluetooth.h',
+              [('serial-bluetooth', '$src/esp32/optional/serial-bluetooth/serial-bluetooth.fs')])
 
 Importation('gen/posix_boot.h', '$src/posix/posix_boot.fs', name='boot')
 Importation('gen/window_boot.h', '$src/windows/windows_boot.fs', header_mode='win', name='boot')