diff --git a/Makefile b/Makefile
index 23a8245..9ce84ab 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ all-kernel:
 	make all -C arch I=$(shell pwd)/include
 
 clean-kernel:
-	make clean -C arch I=$(shell pwd)/include
+	make clean -C arch
 
 run-iso: all-kernel
 	make run -C iso K=$(shell pwd)/arch/kernel
@@ -17,4 +17,4 @@ all-iso: all-kernel
 	make all -C iso K=$(shell pwd)/arch/kernel
 
 clean-iso:
-	make clean -C iso K=$(shell pwd)/arch/kernel
+	make clean -C iso
diff --git a/arch/Makefile b/arch/Makefile
index 017a148..6a9879c 100644
--- a/arch/Makefile
+++ b/arch/Makefile
@@ -1,7 +1,3 @@
-ifneq (ok, $(shell test -d '$(I)' && echo 'ok'))
-$(error 'Include directory "$(I)" does not exist')
-endif
-
 CCPREFIX = i686-elf-
 
 AS = $(CCPREFIX)as
@@ -19,7 +15,7 @@ kernel: $(OBJS)
 	grub-file --is-x86-multiboot2 $@
 
 %.c.o: %.c
-	$(CC) -c $< -o $@ -std=gnu99 -ffreestanding -nostdinc -fno-builtin -fno-stack-protector -Wall -Wextra -I$(I)
+	$(CC) -c $< -o $@ -std=gnu99 -ffreestanding -nostdinc -fno-builtin -fno-stack-protector -Wall -Wextra -I "$(I)"
 
 %.s.o: %.s
 	$(AS) $< -o $@
diff --git a/iso/Makefile b/iso/Makefile
index ed2bc88..67b3d3a 100644
--- a/iso/Makefile
+++ b/iso/Makefile
@@ -1,15 +1,8 @@
-ifneq (ok, $(shell test -f '$(K)' && echo 'ok'))
-$(error 'Kernel "$(K)" does not exist')
-endif
-
-ifneq (ok, $(shell grub-file --is-x86-multiboot2 '$(K)' && echo 'ok'))
-$(error 'Kernel "$(K)" is not compliant with Multiboot 2')
-endif
-
 run: all
 	qemu-system-i386 -cdrom image.iso
 
 all:
+	grub-file --is-x86-multiboot2 "$(K)"
 	cp "$(K)" rootfs/boot/kernelmq
 	grub-mkrescue rootfs -o image.iso