diff --git a/Makefile b/Makefile
index ef51d69079..b532f99f75 100644
--- a/Makefile
+++ b/Makefile
@@ -78,13 +78,6 @@ test/packed_fs.c: Makefile src/ssi.h test/fuzz.c test/data/a.txt
 	$(CC) $(CFLAGS) test/pack.c -o pack
 	$(RUN) ./pack Makefile src/ssi.h test/fuzz.c test/data/a.txt test/data/range.txt > $@
 
-DIR ?= test/data
-OUT ?= packed_fs.c
-mkfs:
-	$(CC) $(CFLAGS) test/pack.c -o pack
-	$(RUN) ./pack -s $(DIR) `find $(DIR) -type f` > $(OUT)
-#	find $(DIR) -type f | sed -e s,^$(DIR),,g -e s,^/,,g
-
 # Check that all external (exported) symbols have "mg_" prefix
 mg_prefix: mongoose.c mongoose.h
 	$(CC) mongoose.c $(CFLAGS) -c -o /tmp/x.o && nm /tmp/x.o | grep ' T ' | grep -v 'mg_' ; test $$? = 1
@@ -165,17 +158,26 @@ arduino: ENV = -v $(CWD)/arduino:/root
 arduino:
 	curl -sL http://downloads.arduino.cc/arduino-1.8.19-linux64.tar.xz | unxz | tar -xf -
 	mv arduino-* $@
+
+arduino-xiao-board:
 	$(DOCKER) mdashnet/cc2 ./arduino/arduino --pref "boardsmanager.additional.urls=https://files.seeedstudio.com/arduino/package_seeeduino_boards_index.json" --save-prefs
 	$(DOCKER) mdashnet/cc2 ./arduino/arduino --pref "compiler.warning_level=all" --save-prefs
 	$(DOCKER) mdashnet/cc2 ./arduino/arduino --install-boards Seeeduino:samd
 
 arduino-xiao: ENV = -v $(CWD)/arduino:/root
-arduino-xiao: arduino
+arduino-xiao: arduino arduino-xiao-board
 	rm -rf tmp; mkdir tmp
 	cp examples/arduino/w5500/w5500.ino tmp/tmp.ino
 	cp mongoose.c mongoose.h examples/arduino/w5500/mongoose_custom.h tmp/
 	$(DOCKER) mdashnet/cc2 ./arduino/arduino --verbose --verify --board Seeeduino:samd:seeed_XIAO_m0 tmp/tmp.ino
 
+arduino-nano: ENV = -v $(CWD)/arduino:/root
+arduino-nano: arduino
+	rm -rf tmp; mkdir tmp
+	cp examples/arduino/w5500/w5500.ino tmp/tmp.ino
+	cp mongoose.c mongoose.h examples/arduino/w5500/mongoose_custom.h tmp/
+	$(DOCKER) mdashnet/cc2 ./arduino/arduino --verbose --verify --board arduino:avr:nano tmp/tmp.ino
+
 mingw++: Makefile mongoose.h $(SRCS)
 	$(DOCKER) mdashnet/mingw x86_64-w64-mingw32-g++ $(SRCS) -W -Wall -Werror -I. $(DEFS) -lwsock32 -o $@.exe
 
diff --git a/examples/arduino/w5500/mongoose_custom.h b/examples/arduino/w5500/mongoose_custom.h
index aee5dfc06c..78b4ca570e 100644
--- a/examples/arduino/w5500/mongoose_custom.h
+++ b/examples/arduino/w5500/mongoose_custom.h
@@ -11,4 +11,5 @@
 #define MG_ENABLE_SOCKET 0
 #define MG_ENABLE_TCPIP 1
 #define mkdir(a, b) (-1)
+#define MG_IO_SIZE 128
 //#define MG_ENABLE_LOG 0
diff --git a/examples/stm32/nucleo-f429zi-cube-baremetal/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-f429zi-cube-baremetal/Core/Inc/mongoose_custom.h
index 0c7a28d59c..d8355cb673 100644
--- a/examples/stm32/nucleo-f429zi-cube-baremetal/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-f429zi-cube-baremetal/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  1
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_STMPACK_ARCH
-
 #define MG_STMPACK_NET 0
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Inc/mongoose_custom.h
index 3fb26f3343..96a2532dd9 100644
--- a/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  0
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_ARCH_FREERTOS
-
 #define MG_STMPACK_NET 1
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_STMPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_STMPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_STMPACK_NET == 2
diff --git a/examples/stm32/nucleo-f429zi-cube-freertos/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-f429zi-cube-freertos/Core/Inc/mongoose_custom.h
index d104a91bec..d9b2f8c700 100644
--- a/examples/stm32/nucleo-f429zi-cube-freertos/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-f429zi-cube-freertos/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  0
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_ARCH_CMSIS_RTOS2
-
 #define MG_STMPACK_NET 0
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_STMPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_STMPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_STMPACK_NET == 2
diff --git a/examples/stm32/nucleo-f429zi-freertos/Makefile b/examples/stm32/nucleo-f429zi-freertos/Makefile
index 87f204bccd..0fd2cdf84b 100644
--- a/examples/stm32/nucleo-f429zi-freertos/Makefile
+++ b/examples/stm32/nucleo-f429zi-freertos/Makefile
@@ -15,7 +15,7 @@ CFLAGS += -IFreeRTOS-Kernel/include
 CFLAGS += -IFreeRTOS-Kernel/portable/GCC/ARM_CM4F -Wno-conversion
 
 SOURCES += mongoose.c  net.c packed_fs.c
-CFLAGS += $(CFLAGS_EXTRA)       # Mongoose options are defined in mongoose_custom.h
+CFLAGS += -DMG_ENABLE_DRIVER_STM32=1 $(CFLAGS_EXTRA) # Mongoose options are defined in mongoose_custom.h
 
 # Example specific build options. See README.md
 CFLAGS += -DHTTP_URL=\"http://0.0.0.0/\"
diff --git a/examples/stm32/nucleo-f429zi-freertos/mongoose_custom.h b/examples/stm32/nucleo-f429zi-freertos/mongoose_custom.h
index 6f0df4ff30..22def7938c 100644
--- a/examples/stm32/nucleo-f429zi-freertos/mongoose_custom.h
+++ b/examples/stm32/nucleo-f429zi-freertos/mongoose_custom.h
@@ -3,6 +3,7 @@
 // See https://mongoose.ws/documentation/#build-options
 #define MG_ARCH MG_ARCH_FREERTOS
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #define MG_IO_SIZE 256
 #define MG_ENABLE_CUSTOM_RANDOM 1
 #define MG_ENABLE_PACKED_FS 1
diff --git a/examples/stm32/nucleo-f429zi-make-baremetal-builtin/Makefile b/examples/stm32/nucleo-f429zi-make-baremetal-builtin/Makefile
index 213971abcb..607f68e620 100644
--- a/examples/stm32/nucleo-f429zi-make-baremetal-builtin/Makefile
+++ b/examples/stm32/nucleo-f429zi-make-baremetal-builtin/Makefile
@@ -11,7 +11,7 @@ SOURCES += cmsis_f4/Source/Templates/gcc/startup_stm32f429xx.s # ST startup file
 # Mongoose-specific source code files and build options. See https://mongoose.ws/documentation/#build-options
 SOURCES += mongoose.c net.c packed_fs.c
 CFLAGS += -DMG_ENABLE_TCPIP=1 -DMG_ARCH=MG_ARCH_NEWLIB -DMG_ENABLE_CUSTOM_MILLIS=1
-CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_ENABLE_PACKED_FS=1 $(CFLAGS_EXTRA)
+CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_ENABLE_PACKED_FS=1 -DMG_ENABLE_DRIVER_STM32=1 $(CFLAGS_EXTRA)
 
 # Example specific build options. See README.md
 CFLAGS += -DHTTP_URL=\"http://0.0.0.0/\"
diff --git a/examples/stm32/nucleo-f429zi-rndis/Makefile b/examples/stm32/nucleo-f429zi-rndis/Makefile
index 157f2688ba..f6531fb152 100644
--- a/examples/stm32/nucleo-f429zi-rndis/Makefile
+++ b/examples/stm32/nucleo-f429zi-rndis/Makefile
@@ -25,7 +25,7 @@ CFLAGS += -Wno-conversion -Wno-sign-conversion
 # Mongoose-specific. See https://mongoose.ws/documentation/#build-options
 SOURCES += mongoose.c 
 CFLAGS += -DMG_ENABLE_TCPIP=1 -DMG_ARCH=MG_ARCH_NEWLIB -DMG_ENABLE_CUSTOM_MILLIS=1
-CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_IO_SIZE=512 $(CFLAGS_EXTRA)
+CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_IO_SIZE=512 -DMG_ENABLE_DRIVER_STM32=1 $(CFLAGS_EXTRA)
 
 ifeq ($(OS),Windows_NT)
   RM = cmd /C del /Q /F /S
diff --git a/examples/stm32/nucleo-f746zg-cube-baremetal/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-f746zg-cube-baremetal/Core/Inc/mongoose_custom.h
index 0c7a28d59c..d8355cb673 100644
--- a/examples/stm32/nucleo-f746zg-cube-baremetal/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-cube-baremetal/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  1
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_STMPACK_ARCH
-
 #define MG_STMPACK_NET 0
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Inc/mongoose_custom.h
index 3fb26f3343..96a2532dd9 100644
--- a/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  0
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_ARCH_FREERTOS
-
 #define MG_STMPACK_NET 1
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_STMPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_STMPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_STMPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-cube-freertos/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-f746zg-cube-freertos/Core/Inc/mongoose_custom.h
index d104a91bec..d9b2f8c700 100644
--- a/examples/stm32/nucleo-f746zg-cube-freertos/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-cube-freertos/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  0
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_ARCH_CMSIS_RTOS2
-
 #define MG_STMPACK_NET 0
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_STMPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_STMPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_STMPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-freertos-tcp/Makefile b/examples/stm32/nucleo-f746zg-freertos-tcp/Makefile
index 98f4953659..99d700955b 100644
--- a/examples/stm32/nucleo-f746zg-freertos-tcp/Makefile
+++ b/examples/stm32/nucleo-f746zg-freertos-tcp/Makefile
@@ -29,7 +29,7 @@ CFLAGS += -DSTM32F7xx -Wno-unused-parameter
 CFLAGS += -DSTM32F746xx -Wno-sign-compare -Wno-undef -Wno-shadow -Wno-array-bounds -Wno-error
 
 SOURCES += mongoose.c  net.c packed_fs.c
-CFLAGS += $(CFLAGS_EXTRA)  # Mongoose options are defined in mongoose_custom.h
+CFLAGS += -DMG_ENABLE_DRIVER_STM32=1 $(CFLAGS_EXTRA)  # Mongoose options are defined in mongoose_custom.h
 
 # Example specific build options. See README.md
 CFLAGS += -DHTTP_URL=\"http://0.0.0.0/\"
diff --git a/examples/stm32/nucleo-f746zg-freertos-tcp/mongoose_custom.h b/examples/stm32/nucleo-f746zg-freertos-tcp/mongoose_custom.h
index 08e7eff913..047eb45036 100644
--- a/examples/stm32/nucleo-f746zg-freertos-tcp/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-freertos-tcp/mongoose_custom.h
@@ -3,6 +3,7 @@
 // See https://mongoose.ws/documentation/#build-options
 #define MG_ARCH MG_ARCH_FREERTOS
 #define MG_ENABLE_FREERTOS_TCP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #define MG_ENABLE_CUSTOM_RANDOM 1
 #define MG_ENABLE_PACKED_FS 1
 
diff --git a/examples/stm32/nucleo-f746zg-freertos/Makefile b/examples/stm32/nucleo-f746zg-freertos/Makefile
index cb817dab40..f3bbc91191 100644
--- a/examples/stm32/nucleo-f746zg-freertos/Makefile
+++ b/examples/stm32/nucleo-f746zg-freertos/Makefile
@@ -15,7 +15,7 @@ CFLAGS += -IFreeRTOS-Kernel/include
 CFLAGS += -IFreeRTOS-Kernel/portable/GCC/ARM_CM7/r0p1 -Wno-conversion
 
 SOURCES += mongoose.c  net.c packed_fs.c
-CFLAGS += $(CFLAGS_EXTRA)  # Mongoose options are defined in mongoose_custom.h
+CFLAGS += -DMG_ENABLE_DRIVER_STM32=1 $(CFLAGS_EXTRA)  # Mongoose options are defined in mongoose_custom.h
 
 # Example specific build options. See README.md
 CFLAGS += -DHTTP_URL=\"http://0.0.0.0/\"
diff --git a/examples/stm32/nucleo-f746zg-freertos/mongoose_custom.h b/examples/stm32/nucleo-f746zg-freertos/mongoose_custom.h
index 6f0df4ff30..22def7938c 100644
--- a/examples/stm32/nucleo-f746zg-freertos/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-freertos/mongoose_custom.h
@@ -3,6 +3,7 @@
 // See https://mongoose.ws/documentation/#build-options
 #define MG_ARCH MG_ARCH_FREERTOS
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #define MG_IO_SIZE 256
 #define MG_ENABLE_CUSTOM_RANDOM 1
 #define MG_ENABLE_PACKED_FS 1
diff --git a/examples/stm32/nucleo-f746zg-keil-baremetal/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-baremetal/mongoose_custom.h
index 9ca06da81c..2a4a222fd6 100644
--- a/examples/stm32/nucleo-f746zg-keil-baremetal/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-baremetal/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos-lwip/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-freertos-lwip/mongoose_custom.h
index a036f80601..f9cea591f1 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos-lwip/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-freertos-lwip/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos-tcp/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-freertos-tcp/mongoose_custom.h
index e3e00c7a45..2efd9df3a3 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos-tcp/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-freertos-tcp/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-freertos/mongoose_custom.h
index 6726972594..b361b5fe07 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-freertos/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/mongoose_custom.h
index a415a6d0e5..b3b3912325 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/mongoose_custom.h
index 6e5c4ceae4..6b53853173 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx-mdk/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-rtx-mdk/mongoose_custom.h
index 503f0c22ed..a6e40a6cea 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx-mdk/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-rtx-mdk/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-rtx/mongoose_custom.h
index 2934901382..20f795645c 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-rtx/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/mongoose_custom.h
index a415a6d0e5..b3b3912325 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/mongoose_custom.h
index cfecebebd8..292eda1c63 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx5/mongoose_custom.h b/examples/stm32/nucleo-f746zg-keil-rtx5/mongoose_custom.h
index c02b5ff2b9..1ebd7fbd85 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx5/mongoose_custom.h
+++ b/examples/stm32/nucleo-f746zg-keil-rtx5/mongoose_custom.h
@@ -65,6 +65,7 @@
 #endif
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-f746zg-make-baremetal-builtin/Makefile b/examples/stm32/nucleo-f746zg-make-baremetal-builtin/Makefile
index 36726779d5..043605845b 100644
--- a/examples/stm32/nucleo-f746zg-make-baremetal-builtin/Makefile
+++ b/examples/stm32/nucleo-f746zg-make-baremetal-builtin/Makefile
@@ -11,7 +11,7 @@ SOURCES += cmsis_f7/Source/Templates/gcc/startup_stm32f746xx.s # ST startup file
 # Mongoose-specific. See https://mongoose.ws/documentation/#build-options
 SOURCES += mongoose.c net.c packed_fs.c
 CFLAGS += -DMG_ENABLE_TCPIP=1 -DMG_ARCH=MG_ARCH_NEWLIB -DMG_ENABLE_CUSTOM_MILLIS=1
-CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_ENABLE_PACKED_FS=1 $(CFLAGS_EXTRA)
+CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_ENABLE_PACKED_FS=1 -DMG_ENABLE_DRIVER_STM32=1 $(CFLAGS_EXTRA)
 
 # Example specific build options. See README.md
 CFLAGS += -DHTTP_URL=\"http://0.0.0.0/\" -DHTTPS_URL=\"https://0.0.0.0/\"
diff --git a/examples/stm32/nucleo-f746zg-rndis/Makefile b/examples/stm32/nucleo-f746zg-rndis/Makefile
index 5730053cd2..8f25ac9ebb 100644
--- a/examples/stm32/nucleo-f746zg-rndis/Makefile
+++ b/examples/stm32/nucleo-f746zg-rndis/Makefile
@@ -25,7 +25,7 @@ CFLAGS += -Wno-conversion -Wno-sign-conversion
 # Mongoose-specific. See https://mongoose.ws/documentation/#build-options
 SOURCES += mongoose.c 
 CFLAGS += -DMG_ENABLE_TCPIP=1 -DMG_ARCH=MG_ARCH_NEWLIB -DMG_ENABLE_CUSTOM_MILLIS=1
-CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_IO_SIZE=512 $(CFLAGS_EXTRA)
+CFLAGS += -DMG_ENABLE_CUSTOM_RANDOM=1 -DMG_IO_SIZE=512 -DMG_ENABLE_DRIVER_STM32=1 $(CFLAGS_EXTRA)
 
 ifeq ($(OS),Windows_NT)
   RM = cmd /C del /Q /F /S
diff --git a/examples/stm32/nucleo-h743zi-cube-baremetal/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-h743zi-cube-baremetal/Core/Inc/mongoose_custom.h
index 0c7a28d59c..632e972152 100644
--- a/examples/stm32/nucleo-h743zi-cube-baremetal/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-h743zi-cube-baremetal/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  1
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_STMPACK_ARCH
-
 #define MG_STMPACK_NET 0
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_CMSISPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32H 1
 #elif MG_CMSISPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_CMSISPACK_NET == 2
diff --git a/examples/stm32/nucleo-h743zi-cube-freertos/Core/Inc/mongoose_custom.h b/examples/stm32/nucleo-h743zi-cube-freertos/Core/Inc/mongoose_custom.h
index d104a91bec..5c4a6d8f59 100644
--- a/examples/stm32/nucleo-h743zi-cube-freertos/Core/Inc/mongoose_custom.h
+++ b/examples/stm32/nucleo-h743zi-cube-freertos/Core/Inc/mongoose_custom.h
@@ -8,20 +8,16 @@
 #endif
 
 #define MG_ENABLE_PACKED_FS  1
-
 #define MG_ENABLE_CUSTOM_MILLIS  0
-
 #define MG_ENABLE_MBEDTLS  0
-
 #define MG_ARCH MG_ARCH_CMSIS_RTOS2
-
 #define MG_STMPACK_NET 0
-
 #define MG_ENABLE_CUSTOM_RANDOM  1
 
 // Translate to Mongoose macros
 #if MG_STMPACK_NET == 0
 #define MG_ENABLE_TCPIP 1
+#define MG_ENABLE_DRIVER_STM32H 1
 #elif MG_STMPACK_NET == 1
 #define MG_ENABLE_LWIP 1
 #elif MG_STMPACK_NET == 2
diff --git a/mongoose.c b/mongoose.c
index 7cbb4f8bd5..0148f26948 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -6702,7 +6702,7 @@ struct mg_tcpip_driver mg_tcpip_driver_imxrt1020 = {
 #endif
 
 
-#if MG_ENABLE_TCPIP && MG_ENABLE_DRIVER_STM32
+#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_STM32) && MG_ENABLE_DRIVER_STM32
 struct stm32_eth {
   volatile uint32_t MACCR, MACFFR, MACHTHR, MACHTLR, MACMIIAR, MACMIIDR, MACFCR,
       MACVLANTR, RESERVED0[2], MACRWUFFR, MACPMTCSR, RESERVED1, MACDBGR, MACSR,
@@ -8144,8 +8144,9 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
       uint32_t rem_ip;
       memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
       MG_DEBUG(("SEQ != ACK: %x %x %x", seq, s->ack, ack));
-      tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK, c->loc.port,
-           c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
+      tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK,
+             c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "",
+             0);
     }
   } else if (io->size - io->len < pkt->pay.len &&
              !mg_iobuf_resize(io, io->len + pkt->pay.len)) {
@@ -8371,7 +8372,7 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t uptime_ms) {
     if (ifp->now >= ifp->lease_expire) {
       ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;  // expired, release IP
       onstatechange(ifp);
-    } else if (ifp->now + 30 * 60 * 1000 > ifp->lease_expire &&
+    } else if (ifp->now + 30UL * 60UL * 1000UL > ifp->lease_expire &&
                ((ifp->now / 1000) % 60) == 0) {
       // hack: 30 min before deadline, try to rebind (4.3.6) every min
       tx_dhcp_request_re(ifp, (uint8_t *) broadcast, ifp->ip, 0xffffffff);
diff --git a/mongoose.h b/mongoose.h
index e8d84f218d..92ea0fbab4 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -755,7 +755,7 @@ struct timeval {
 #endif
 
 #ifndef MG_MAX_RECV_SIZE
-#define MG_MAX_RECV_SIZE (3 * 1024 * 1024)  // Maximum recv IO buffer size
+#define MG_MAX_RECV_SIZE (3UL * 1024UL * 1024UL)  // Maximum recv IO buffer size
 #endif
 
 #ifndef MG_DATA_SIZE
@@ -1630,7 +1630,7 @@ void mg_rpc_list(struct mg_rpc_req *r);
 
 
 
-struct mg_tcpip_if;  // MIP network interface
+struct mg_tcpip_if;  // Mongoose TCP/IP network interface
 
 struct mg_tcpip_driver {
   bool (*init)(struct mg_tcpip_if *);                         // Init driver
@@ -1646,8 +1646,8 @@ struct mg_tcpip_if {
   struct mg_str tx;                // Output (TX) buffer
   bool enable_dhcp_client;         // Enable DCHP client
   bool enable_dhcp_server;         // Enable DCHP server
-  bool enable_crc32_check;         // Do a CRC check on rx frames and strip it
-  bool enable_mac_check;           // Do a MAC check on rx frames
+  bool enable_crc32_check;         // Do a CRC check on RX frames and strip it
+  bool enable_mac_check;           // Do a MAC check on RX frames
   struct mg_tcpip_driver *driver;  // Low level driver
   void *driver_data;               // Driver-specific data
   struct mg_mgr *mgr;              // Mongoose event manager
@@ -1687,12 +1687,6 @@ struct mg_tcpip_spi {
   void (*end)(void *);              // SPI end: slave select high
   uint8_t (*txn)(void *, uint8_t);  // SPI transaction: write 1 byte, read reply
 };
-
-#if !defined(MG_ENABLE_DRIVER_STM32H) && !defined(MG_ENABLE_DRIVER_TM4C)
-#define MG_ENABLE_DRIVER_STM32 1
-#else
-#define MG_ENABLE_DRIVER_STM32 0
-#endif
 #endif
 
 
diff --git a/src/config.h b/src/config.h
index 80012f4707..7a99eb9c1e 100644
--- a/src/config.h
+++ b/src/config.h
@@ -90,7 +90,7 @@
 #endif
 
 #ifndef MG_MAX_RECV_SIZE
-#define MG_MAX_RECV_SIZE (3 * 1024 * 1024)  // Maximum recv IO buffer size
+#define MG_MAX_RECV_SIZE (3UL * 1024UL * 1024UL)  // Maximum recv IO buffer size
 #endif
 
 #ifndef MG_DATA_SIZE
diff --git a/src/tcpip/driver_stm32.c b/src/tcpip/driver_stm32.c
index 4135cb8b78..3a216ed9c7 100644
--- a/src/tcpip/driver_stm32.c
+++ b/src/tcpip/driver_stm32.c
@@ -1,6 +1,6 @@
 #include "tcpip.h"
 
-#if MG_ENABLE_TCPIP && MG_ENABLE_DRIVER_STM32
+#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_STM32) && MG_ENABLE_DRIVER_STM32
 struct stm32_eth {
   volatile uint32_t MACCR, MACFFR, MACHTHR, MACHTLR, MACMIIAR, MACMIIDR, MACFCR,
       MACVLANTR, RESERVED0[2], MACRWUFFR, MACPMTCSR, RESERVED1, MACDBGR, MACSR,
diff --git a/src/tcpip/tcpip.c b/src/tcpip/tcpip.c
index f96b859730..c500709da1 100644
--- a/src/tcpip/tcpip.c
+++ b/src/tcpip/tcpip.c
@@ -582,8 +582,9 @@ static void read_conn(struct mg_connection *c, struct pkt *pkt) {
       uint32_t rem_ip;
       memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
       MG_DEBUG(("SEQ != ACK: %x %x %x", seq, s->ack, ack));
-      tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK, c->loc.port,
-           c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
+      tx_tcp((struct mg_tcpip_if *) c->mgr->priv, s->mac, rem_ip, TH_ACK,
+             c->loc.port, c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), "",
+             0);
     }
   } else if (io->size - io->len < pkt->pay.len &&
              !mg_iobuf_resize(io, io->len + pkt->pay.len)) {
@@ -809,7 +810,7 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t uptime_ms) {
     if (ifp->now >= ifp->lease_expire) {
       ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;  // expired, release IP
       onstatechange(ifp);
-    } else if (ifp->now + 30 * 60 * 1000 > ifp->lease_expire &&
+    } else if (ifp->now + 30UL * 60UL * 1000UL > ifp->lease_expire &&
                ((ifp->now / 1000) % 60) == 0) {
       // hack: 30 min before deadline, try to rebind (4.3.6) every min
       tx_dhcp_request_re(ifp, (uint8_t *) broadcast, ifp->ip, 0xffffffff);
diff --git a/src/tcpip/tcpip.h b/src/tcpip/tcpip.h
index 93780ac646..c7aed96418 100644
--- a/src/tcpip/tcpip.h
+++ b/src/tcpip/tcpip.h
@@ -5,7 +5,7 @@
 #include "net.h"
 #include "queue.h"
 
-struct mg_tcpip_if;  // MIP network interface
+struct mg_tcpip_if;  // Mongoose TCP/IP network interface
 
 struct mg_tcpip_driver {
   bool (*init)(struct mg_tcpip_if *);                         // Init driver
@@ -21,8 +21,8 @@ struct mg_tcpip_if {
   struct mg_str tx;                // Output (TX) buffer
   bool enable_dhcp_client;         // Enable DCHP client
   bool enable_dhcp_server;         // Enable DCHP server
-  bool enable_crc32_check;         // Do a CRC check on rx frames and strip it
-  bool enable_mac_check;           // Do a MAC check on rx frames
+  bool enable_crc32_check;         // Do a CRC check on RX frames and strip it
+  bool enable_mac_check;           // Do a MAC check on RX frames
   struct mg_tcpip_driver *driver;  // Low level driver
   void *driver_data;               // Driver-specific data
   struct mg_mgr *mgr;              // Mongoose event manager
@@ -62,10 +62,4 @@ struct mg_tcpip_spi {
   void (*end)(void *);              // SPI end: slave select high
   uint8_t (*txn)(void *, uint8_t);  // SPI transaction: write 1 byte, read reply
 };
-
-#if !defined(MG_ENABLE_DRIVER_STM32H) && !defined(MG_ENABLE_DRIVER_TM4C)
-#define MG_ENABLE_DRIVER_STM32 1
-#else
-#define MG_ENABLE_DRIVER_STM32 0
-#endif
 #endif