diff --git a/lib/asdf.sh b/lib/asdf.sh
index ee0a85f4..a57d78c9 100755
--- a/lib/asdf.sh
+++ b/lib/asdf.sh
@@ -20,7 +20,7 @@ install_command() {
   check_if_source_exists $source_path
 
   IFS=':' read -a version_info <<< "$full_version"
-  if [ "${version_info[0]}" -e "tag" ] || [ "${version_info[0]}" -e "commit" ]
+  if [ "${version_info[0]}" = "tag" ] || [ "${version_info[0]}" = "commit" ]
   then
     local install_type="${version_info[0]}"
     local version="${version_info[1]}"
diff --git a/sources/erlang/install b/sources/erlang/install
index 0df7b897..8bfea63d 100755
--- a/sources/erlang/install
+++ b/sources/erlang/install
@@ -61,7 +61,7 @@ get_download_url() {
   local install_type=$1
   local version=$2
 
-  if [ "$install_type" -e "version" ]
+  if [ "$install_type" = "version" ]
   then
     echo "http://www.erlang.org/download/otp_src_${version}.tar.gz"
   else