diff --git a/bin/git-missing b/bin/git-missing
index 7a7c8b5..3a90410 100755
--- a/bin/git-missing
+++ b/bin/git-missing
@@ -2,9 +2,9 @@
 
 # grab first two non-option arguments
 for arg in $*; do
-    if [[ $arg != -* ]]; then
-        test -z "$firstbranch" && firstbranch=$arg && continue
-        test -z "$secondbranch" && secondbranch=$arg && continue
+    if [ -n "${arg}" ]; then
+        test -z "$firstbranch" && firstbranch="${arg}" && continue
+        test -z "$secondbranch" && secondbranch="${arg}" && continue
     else
         # add anything else to a passthrough
         passthrough="$passthrough $arg"