diff --git a/Formula/tractorgen.rb b/Formula/tractorgen.rb
index 2e625866d5..30d76518f3 100644
--- a/Formula/tractorgen.rb
+++ b/Formula/tractorgen.rb
@@ -20,13 +20,13 @@ class Tractorgen < Formula
   end
 
   test do
-    expected = <<-'EOS'
-         r-
-        _|
-       / |_\_    \\
-      |    |o|----\\
-      |_______\_--_\\
-     (O)_O_O_(O)    \\
+    expected = <<~'EOS'.gsub(/^/, "     ") # needs to be indented five spaces
+          r-
+         _|
+        / |_\_    \\
+       |    |o|----\\
+       |_______\_--_\\
+      (O)_O_O_(O)    \\
     EOS
     assert_equal expected, shell_output("#{bin}/tractorgen 4")
   end