diff --git a/src/util/signature.cr b/src/util/signature.cr
index bb16bed..74c8b8e 100644
--- a/src/util/signature.cr
+++ b/src/util/signature.cr
@@ -67,7 +67,9 @@ class Dir
         else
           # Only add its signature value to `signatures` when it is a
           #   supported file
-          signatures << fn if ArchiveEntry.is_valid?(fn) || is_supported_image_file(fn)
+          if ArchiveEntry.is_valid?(fn) || is_supported_image_file(fn)
+            signatures << fn
+          end
         end
         Fiber.yield
       end