diff --git a/Makefile b/Makefile
index 165eec5..b746adf 100644
--- a/Makefile
+++ b/Makefile
@@ -3,10 +3,10 @@ include Makefile.inputs
 ###################
 # Hidden vars
 
-export SHELL = /bin/sh
+export SHELL := /bin/sh
 # Cache
-export DNF_CACHE = 
-export PACKAGE_MANAGER = dnf
+export DNF_CACHE := 
+export PACKAGE_MANAGER := dnf
 
 # Functions
 ## Formatting = lowercase
@@ -24,20 +24,20 @@ export install_pkg
 
 # Generated/internal vars
 ## Formatting = _UPPERCASE
-export _BASE_DIR = $(shell pwd)
-_IMAGE_REPO_ESCAPED = $(subst /,\/,$(IMAGE_REPO))
-_IMAGE_REPO_DOUBLE_ESCAPED = $(subst \,\\\,$(_IMAGE_REPO_ESCAPED))
-_LORAX_ARGS = 
-_LORAX_TEMPLATES = $(call get_templates,install)
-_REPO_FILES = $(subst /etc/yum.repos.d,repos,$(REPOS))
-_TEMP_DIR = $(shell mktemp -d)
-_TEMPLATE_VARS = ARCH _BASE_DIR IMAGE_NAME IMAGE_REPO _IMAGE_REPO_DOUBLE_ESCAPED _IMAGE_REPO_ESCAPED IMAGE_TAG REPOS _RHEL VARIANT VERSION WEB_UI
-_VOLID = $(firstword $(subst -, ,$(IMAGE_NAME)))-$(ARCH)-$(IMAGE_TAG)
+export _BASE_DIR           := $(shell pwd)
+_IMAGE_REPO_ESCAPED        := $(subst /,\/,$(IMAGE_REPO))
+_IMAGE_REPO_DOUBLE_ESCAPED := $(subst \,\\\,$(_IMAGE_REPO_ESCAPED))
+_LORAX_ARGS                := 
+_LORAX_TEMPLATES           := $(call get_templates,install)
+_REPO_FILES                := $(subst /etc/yum.repos.d,repos,$(REPOS))
+_TEMP_DIR                  := $(shell mktemp -d)
+_TEMPLATE_VARS             := ARCH _BASE_DIR IMAGE_NAME IMAGE_REPO _IMAGE_REPO_DOUBLE_ESCAPED _IMAGE_REPO_ESCAPED IMAGE_TAG REPOS _RHEL VARIANT VERSION WEB_UI
+_VOLID                     := $(firstword $(subst -, ,$(IMAGE_NAME)))-$(ARCH)-$(IMAGE_TAG)
 
 ifeq ($(findstring redhat.repo,$(REPOS)),redhat.repo)
-_RHEL = true
+_RHEL := true
 else
-_RHEL = false
+_RHEL := false
 endif
 
 ifeq ($(_RHEL),true)
@@ -66,7 +66,7 @@ _LORAX_TEMPLATES += $(call get_templates,secureboot)
 _TEMPLATE_VARS   += ENROLLMENT_PASSWORD
 endif
 
-_SUBDIRS = container external flatpak_refs lorax_templates repos xorriso test
+_SUBDIRS := container external flatpak_refs lorax_templates repos xorriso test
 
 # Create checksum
 ## Default action
@@ -103,7 +103,7 @@ results/images/boot.iso: external/lorax/branch-$(VERSION) $(filter lorax_templat
 	$(if $(wildcard $(_TEMP_DIR)/macros.image-language-conf),mv -f $(_TEMP_DIR)/macros.image-language-conf /etc/rpm/macros.image-language-conf)
 
 
-FILES_TO_CLEAN = $(wildcard build debugdata pkglists results original-pkgsizes.txt final-pkgsizes.txt lorax.conf *.iso *log)
+FILES_TO_CLEAN := $(wildcard build debugdata pkglists results original-pkgsizes.txt final-pkgsizes.txt lorax.conf *.iso *log)
 .PHONY: clean
 clean:
 	rm -Rf $(FILES_TO_CLEAN)
diff --git a/Makefile.flatpak b/Makefile.flatpak
index b0d332f..6279934 100644
--- a/Makefile.flatpak
+++ b/Makefile.flatpak
@@ -1,18 +1,18 @@
 ifneq ($(FLATPAK_DIR),)
-_FLATPAK_REPO_GPG = $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^GPGKey=' | cut -d= -f2)
-export _FLATPAK_REPO_URL = $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^URL=' | cut -d= -f2)
+_FLATPAK_REPO_GPG := $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^GPGKey=' | cut -d= -f2)
+export _FLATPAK_REPO_URL := $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^URL=' | cut -d= -f2)
 _LORAX_ARGS      += -i flatpak-libs
 _LORAX_TEMPLATES += $(call get_templates,flatpak)
 _TEMPLATE_VARS   += FLATPAK_DIR FLATPAK_REMOTE_NAME FLATPAK_REMOTE_REFS FLATPAK_REMOTE_URL _FLATPAK_REPO_GPG _FLATPAK_REPO_URL
 else
 ifneq ($(FLATPAK_REMOTE_REFS_DIR),)
-COLLECTED_REFS = $(foreach file,$(filter-out README.md Makefile,$(wildcard $(FLATPAK_REMOTE_REFS_DIR)/*)),$(shell cat $(file)))
+COLLECTED_REFS := $(foreach file,$(filter-out README.md Makefile,$(wildcard $(FLATPAK_REMOTE_REFS_DIR)/*)),$(shell cat $(file)))
 FLATPAK_REMOTE_REFS += $(sort $(COLLECTED_REFS))
 endif
 
 ifneq ($(FLATPAK_REMOTE_REFS),)
-_FLATPAK_REPO_GPG = $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^GPGKey=' | cut -d= -f2)
-export _FLATPAK_REPO_URL = $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^URL=' | cut -d= -f2)
+_FLATPAK_REPO_GPG := $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^GPGKey=' | cut -d= -f2)
+export _FLATPAK_REPO_URL := $(shell curl -L $(FLATPAK_REMOTE_URL) | grep -i '^URL=' | cut -d= -f2)
 _LORAX_ARGS      += -i flatpak-libs
 _LORAX_TEMPLATES += $(call get_templates,flatpak) \
 					external/fedora-lorax-templates/ostree-based-installer/lorax-embed-flatpaks.tmpl
diff --git a/Makefile.inputs b/Makefile.inputs
index c425bea..ad4f333 100644
--- a/Makefile.inputs
+++ b/Makefile.inputs
@@ -1,24 +1,24 @@
 # Configuration vars
 ## Formatting = UPPERCASE
 # General
-export ADDITIONAL_TEMPLATES    =
-export ARCH                    = x86_64
-export EXTRA_BOOT_PARAMS       =
-export IMAGE_NAME              = base
-export IMAGE_REPO              = quay.io/fedora-ostree-desktops
-export IMAGE_TAG               = $(VERSION)
-       REPOS                   = $(subst :,\:,$(wildcard /etc/yum.repos.d/*.repo))
-export ROOTFS_SIZE             = 4
-export VARIANT                 = Server
-export VERSION                 = 39
-export WEB_UI                  = false
+export ADDITIONAL_TEMPLATES    :=
+export ARCH                    := x86_64
+export EXTRA_BOOT_PARAMS       :=
+export IMAGE_NAME              := base
+export IMAGE_REPO              := quay.io/fedora-ostree-desktops
+export IMAGE_TAG                = $(VERSION)
+       REPOS                   := $(subst :,\:,$(wildcard /etc/yum.repos.d/*.repo))
+export ROOTFS_SIZE             := 4
+export VARIANT                 := Server
+export VERSION                 := 39
+export WEB_UI                  := false
 # Flatpak
-export FLATPAK_REMOTE_NAME     = flathub
-export FLATPAK_REMOTE_URL      = https://flathub.org/repo/flathub.flatpakrepo
-export FLATPAK_REMOTE_REFS     =
-export FLATPAK_REMOTE_REFS_DIR =
-export FLATPAK_DIR             =
+export FLATPAK_REMOTE_NAME     := flathub
+export FLATPAK_REMOTE_URL      := https://flathub.org/repo/flathub.flatpakrepo
+export FLATPAK_REMOTE_REFS     :=
+export FLATPAK_REMOTE_REFS_DIR :=
+export FLATPAK_DIR             :=
 # Secure boot
-export ENROLLMENT_PASSWORD     =
-export SECURE_BOOT_KEY_URL     =
-export ISO_NAME                = build/deploy.iso
\ No newline at end of file
+export ENROLLMENT_PASSWORD     :=
+export SECURE_BOOT_KEY_URL     :=
+export ISO_NAME                := build/deploy.iso
\ No newline at end of file
diff --git a/test/iso/Makefile b/test/iso/Makefile
index ec99e88..b154ec6 100644
--- a/test/iso/Makefile
+++ b/test/iso/Makefile
@@ -15,9 +15,9 @@ mnt/iso:
 	sudo mount -t squashfs -o loop mnt/iso/images/install.img mnt/install
 
 clean:
-	sudo umount /mnt/install || true
-	sudo umount /mnt/iso || true
-	sudo rmdir /mnt/install /mnt/iso
+	sudo umount mnt/install || true
+	sudo umount mnt/iso || true
+	sudo rmdir mnt/install /mnt/iso
 
 install-deps:
 	$(install_pkg) isomd5sum coreutils squashfs-tools curl