diff --git a/bin/preview.sh b/bin/preview.sh
index f9c8db1..ed08075 100755
--- a/bin/preview.sh
+++ b/bin/preview.sh
@@ -28,8 +28,9 @@ if [ ! -r "$FILE" ]; then
   exit 1
 fi
 
+FILE_LENGTH=${#FILE}
 MIME=$(file --dereference --mime "$FILE")
-if [[ "$MIME" =~ binary ]]; then
+if [[ "${MIME:FILE_LENGTH}" =~ binary ]]; then
   echo "$MIME"
   exit 0
 fi