diff --git a/Makefile.inputs b/Makefile.inputs
index ad4f333..c425bea 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/action.yml b/action.yml
index 5e1435a..005dea2 100644
--- a/action.yml
+++ b/action.yml
@@ -198,8 +198,8 @@ runs:
           DNF_CACHE="/cache/dnf" \
           ENROLLMENT_PASSWORD="${{ inputs.enrollment_password }}" \
           FLATPAK_REMOTE_NAME="${{ inputs.flatpak_remote_name }}" \
-          FLATPAK_REMOTE_REFS="${{ inputs.flatpak_remote_refs }}" \
-          FLATPAK_REMOTE_REFS_DIR="${{ inputs.flatpak_remote_refs_dir }}" \
+          ${{ inputs.flatpak_remote_refs && format('FLATPAK_REMOTE_REFS="{0}"', inputs.flatpak_remote_refs) || ''}} \
+          ${{ inputs.flatpak_remote_refs_dir && format('FLATPAK_REMOTE_REFS_DIR="{0}"', inputs.flatpak_remote_refs_dir) || ''}} \
           FLATPAK_REMOTE_URL="${{ inputs.flatpak_remote_url }}" \
           FLATPAK_DIR="${{ steps.flatpak_dependencies.outputs.flatpak_dir && format('/github/workspace/{0}', steps.flatpak_dependencies.outputs.flatpak_dir) || '' }}" \
           IMAGE_NAME="${{ inputs.image_name }}" \
diff --git a/repos/Makefile b/repos/Makefile
index ba0b6d6..63e2f7f 100644
--- a/repos/Makefile
+++ b/repos/Makefile
@@ -3,8 +3,8 @@ repos: $(_REPO_FILES)
 # Step 2: Replace vars in repo files
 %.repo: /etc/yum.repos.d/%.repo
 	cp /etc/yum.repos.d/$*.repo           $*.repo
-	sed -i "s/\$$releasever/${VERSION}/g" $*.repo
-	sed -i "s/\$$basearch/${ARCH}/g"      $*.repo
+	sed -i "s/\$$releasever/$(VERSION)/g" $*.repo
+	sed -i "s/\$$basearch/$(ARCH)/g"      $*.repo
 
 install-deps: