diff --git a/part10-multicore/Makefile.gcc b/part10-multicore/Makefile.gcc
index 9fe0560..4acdd75 100644
--- a/part10-multicore/Makefile.gcc
+++ b/part10-multicore/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part10-multicore/multicore.h b/part10-multicore/multicore.h
index 4c3dc0f..56d8cfb 100644
--- a/part10-multicore/multicore.h
+++ b/part10-multicore/multicore.h
@@ -1,7 +1,7 @@
-extern unsigned int spin_cpu0;
-extern unsigned int spin_cpu1;
-extern unsigned int spin_cpu2;
-extern unsigned int spin_cpu3;
+extern unsigned long spin_cpu0;
+extern unsigned long spin_cpu1;
+extern unsigned long spin_cpu2;
+extern unsigned long spin_cpu3;
 
 void start_core1(void (*func)(void));
 void start_core2(void (*func)(void));
diff --git a/part11-breakout-smp/Makefile.gcc b/part11-breakout-smp/Makefile.gcc
index 023aa68..cc845ee 100644
--- a/part11-breakout-smp/Makefile.gcc
+++ b/part11-breakout-smp/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c lib/*.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part11-breakout-smp/include/multicore.h b/part11-breakout-smp/include/multicore.h
index 4c3dc0f..56d8cfb 100644
--- a/part11-breakout-smp/include/multicore.h
+++ b/part11-breakout-smp/include/multicore.h
@@ -1,7 +1,7 @@
-extern unsigned int spin_cpu0;
-extern unsigned int spin_cpu1;
-extern unsigned int spin_cpu2;
-extern unsigned int spin_cpu3;
+extern unsigned long spin_cpu0;
+extern unsigned long spin_cpu1;
+extern unsigned long spin_cpu2;
+extern unsigned long spin_cpu3;
 
 void start_core1(void (*func)(void));
 void start_core2(void (*func)(void));
diff --git a/part12-wgt/include/multicore.h b/part12-wgt/include/multicore.h
index 4c3dc0f..56d8cfb 100644
--- a/part12-wgt/include/multicore.h
+++ b/part12-wgt/include/multicore.h
@@ -1,7 +1,7 @@
-extern unsigned int spin_cpu0;
-extern unsigned int spin_cpu1;
-extern unsigned int spin_cpu2;
-extern unsigned int spin_cpu3;
+extern unsigned long spin_cpu0;
+extern unsigned long spin_cpu1;
+extern unsigned long spin_cpu2;
+extern unsigned long spin_cpu3;
 
 void start_core1(void (*func)(void));
 void start_core2(void (*func)(void));
diff --git a/part13-interrupts/Makefile.gcc b/part13-interrupts/Makefile.gcc
index fa40d98..bb4ce8a 100644
--- a/part13-interrupts/Makefile.gcc
+++ b/part13-interrupts/Makefile.gcc
@@ -1,8 +1,8 @@
 CFILES = $(wildcard *.c lib/*.c kernel/*.c)
 SFILES = $(wildcard boot/*.S lib/*.S kernel/*.S)
 OFILES = $(CFILES:.c=.o) $(SFILES:.S=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part13-interrupts/include/multicore.h b/part13-interrupts/include/multicore.h
index 4c3dc0f..56d8cfb 100644
--- a/part13-interrupts/include/multicore.h
+++ b/part13-interrupts/include/multicore.h
@@ -1,7 +1,7 @@
-extern unsigned int spin_cpu0;
-extern unsigned int spin_cpu1;
-extern unsigned int spin_cpu2;
-extern unsigned int spin_cpu3;
+extern unsigned long spin_cpu0;
+extern unsigned long spin_cpu1;
+extern unsigned long spin_cpu2;
+extern unsigned long spin_cpu3;
 
 void start_core1(void (*func)(void));
 void start_core2(void (*func)(void));
diff --git a/part14-spi-ethernet/Makefile.gcc b/part14-spi-ethernet/Makefile.gcc
index d8316fd..94770c4 100644
--- a/part14-spi-ethernet/Makefile.gcc
+++ b/part14-spi-ethernet/Makefile.gcc
@@ -1,8 +1,8 @@
 CFILES = $(wildcard *.c lib/*.c kernel/*.c net/*.c)
 SFILES = $(wildcard boot/*.S lib/*.S kernel/*.S)
 OFILES = $(CFILES:.c=.o) $(SFILES:.S=.o)
-GCCFLAGS = -Wall -O0 -ffreestanding -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part14-spi-ethernet/include/multicore.h b/part14-spi-ethernet/include/multicore.h
index 4c3dc0f..56d8cfb 100644
--- a/part14-spi-ethernet/include/multicore.h
+++ b/part14-spi-ethernet/include/multicore.h
@@ -1,7 +1,7 @@
-extern unsigned int spin_cpu0;
-extern unsigned int spin_cpu1;
-extern unsigned int spin_cpu2;
-extern unsigned int spin_cpu3;
+extern unsigned long spin_cpu0;
+extern unsigned long spin_cpu1;
+extern unsigned long spin_cpu2;
+extern unsigned long spin_cpu3;
 
 void start_core1(void (*func)(void));
 void start_core2(void (*func)(void));
diff --git a/part15-tcpip-webserver/Makefile.gcc b/part15-tcpip-webserver/Makefile.gcc
index cb4b843..4674ebf 100644
--- a/part15-tcpip-webserver/Makefile.gcc
+++ b/part15-tcpip-webserver/Makefile.gcc
@@ -1,8 +1,8 @@
 CFILES = $(wildcard *.c lib/*.c kernel/*.c net/*.c tcpip/*.c)
 SFILES = $(wildcard boot/*.S lib/*.S kernel/*.S)
 OFILES = $(CFILES:.c=.o) $(SFILES:.S=.o)
-GCCFLAGS = -Wall -O0 -ffreestanding -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part15-tcpip-webserver/include/multicore.h b/part15-tcpip-webserver/include/multicore.h
index 4c3dc0f..56d8cfb 100644
--- a/part15-tcpip-webserver/include/multicore.h
+++ b/part15-tcpip-webserver/include/multicore.h
@@ -1,7 +1,7 @@
-extern unsigned int spin_cpu0;
-extern unsigned int spin_cpu1;
-extern unsigned int spin_cpu2;
-extern unsigned int spin_cpu3;
+extern unsigned long spin_cpu0;
+extern unsigned long spin_cpu1;
+extern unsigned long spin_cpu2;
+extern unsigned long spin_cpu3;
 
 void start_core1(void (*func)(void));
 void start_core2(void (*func)(void));
diff --git a/part2-building/Makefile.gcc b/part2-building/Makefile.gcc
index ae02b77..f1cfea7 100644
--- a/part2-building/Makefile.gcc
+++ b/part2-building/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part3-helloworld/Makefile.gcc b/part3-helloworld/Makefile.gcc
index ae02b77..f1cfea7 100644
--- a/part3-helloworld/Makefile.gcc
+++ b/part3-helloworld/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part4-miniuart/Makefile.gcc b/part4-miniuart/Makefile.gcc
index ae02b77..f1cfea7 100644
--- a/part4-miniuart/Makefile.gcc
+++ b/part4-miniuart/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part5-framebuffer/Makefile.gcc b/part5-framebuffer/Makefile.gcc
index ae02b77..f1cfea7 100644
--- a/part5-framebuffer/Makefile.gcc
+++ b/part5-framebuffer/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part6-breakout/Makefile.gcc b/part6-breakout/Makefile.gcc
index ae02b77..f1cfea7 100644
--- a/part6-breakout/Makefile.gcc
+++ b/part6-breakout/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part7-bluetooth/Makefile.gcc b/part7-bluetooth/Makefile.gcc
index a22d069..373731d 100644
--- a/part7-bluetooth/Makefile.gcc
+++ b/part7-bluetooth/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part8-breakout-ble/Makefile.gcc b/part8-breakout-ble/Makefile.gcc
index a22d069..373731d 100644
--- a/part8-breakout-ble/Makefile.gcc
+++ b/part8-breakout-ble/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img
 
diff --git a/part8-breakout-ble/Makefile.gcc.windows b/part8-breakout-ble/Makefile.gcc.windows
deleted file mode 100644
index ac37e4a..0000000
--- a/part8-breakout-ble/Makefile.gcc.windows
+++ /dev/null
@@ -1,22 +0,0 @@
-CFILES = $(wildcard *.c)
-OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ..\..\gcc-arm-10.2-2020.11-mingw-w64-i686-aarch64-none-elf\bin
-
-all: clean kernel8.img
-
-boot.o: boot.S
-	$(GCCPATH)\aarch64-none-elf-gcc $(GCCFLAGS) -c boot.S -o boot.o
-
-BCM4345C0.o : BCM4345C0.hcd
-	$(GCCPATH)\aarch64-none-elf-objcopy -I binary -O elf64-littleaarch64 -B aarch64 $< $@
-
-%.o: %.c
-	$(GCCPATH)\aarch64-none-elf-gcc $(GCCFLAGS) -c $< -o $@
-
-kernel8.img: boot.o $(OFILES) BCM4345C0.o
-	$(GCCPATH)\aarch64-none-elf-ld -nostdlib boot.o $(OFILES) BCM4345C0.o -T link.ld -o kernel8.elf
-	$(GCCPATH)\aarch64-none-elf-objcopy -O binary kernel8.elf kernel8.img
-
-clean:
-	del kernel8.elf *.o *.img
diff --git a/part9-sound/Makefile.gcc b/part9-sound/Makefile.gcc
index 9fe0560..4acdd75 100644
--- a/part9-sound/Makefile.gcc
+++ b/part9-sound/Makefile.gcc
@@ -1,7 +1,7 @@
 CFILES = $(wildcard *.c)
 OFILES = $(CFILES:.c=.o)
-GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
-GCCPATH = ../../gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf/bin
+GCCFLAGS = -Wall -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles -mstrict-align
+GCCPATH = ../../arm-gnu-toolchain-13.2.Rel1-darwin-arm64-aarch64-none-elf/bin
 
 all: clean kernel8.img