diff --git a/install.sh b/install.sh
index 0e74e80..f13e2cc 100755
--- a/install.sh
+++ b/install.sh
@@ -27,7 +27,7 @@ zaf_err() {
 
 # Download tgz and extract to tmpdir
 zaf_download_files() {
-	[ -n $ZAF_DIR ] && zaf_err "ZAF_DIR not set!"
+	[ -z $ZAF_DIR ] && zaf_err "ZAF_DIR not set!"
 	rm -rf $ZAF_DIR
 	zaf_fetch_url $ZAF_URL/archive/$ZAF_GITBRANCH.tar.gz | tar -f - -C $ZAF_TMP_DIR -zx && mv $ZAF_TMP_DIR/zaf-$ZAF_GITBRANCH $ZAF_DIR \
  		|| zaf_err "Cannot download and unpack zaf!"
diff --git a/zaf b/zaf
index 350a56a..d8745f3 100755
--- a/zaf
+++ b/zaf
@@ -242,7 +242,6 @@ self-upgrade)
 	shift
 	[ -z "$1" ] && auto=auto
 	zaf_os_specific zaf_check_deps zaf && zaf_err "Zaf is installed as system package. Cannot self-upgrade."
-	rm -rf /tmp/zaf-installer && mkdir /tmp/zaf-installer
 	if ! which curl >/dev/null;
 	then
 		zaf_err "Curl not found. Cannot continue. Please install it."