diff --git a/kiss b/kiss
index d2c2bbd..8cca5e5 100755
--- a/kiss
+++ b/kiss
@@ -12,6 +12,7 @@ log() {
 }
 
 source_type() {
+    [ -z "$1" ]                && return 1  # No file.
     [ -f "$1" ]                && return 2  # Local file.
     [ -f "$src_dir/${1##*/}" ] && return 3  # Cached downloaded file.
     [ -z "${1##git:*}" ]       && return 4  # Git repository.