diff --git a/bundler/lib/bundler/cli/exec.rb b/bundler/lib/bundler/cli/exec.rb
index f81cd5d2c406..c0b488cc4ece 100644
--- a/bundler/lib/bundler/cli/exec.rb
+++ b/bundler/lib/bundler/cli/exec.rb
@@ -69,11 +69,13 @@ def process_title(file, args)
     end
 
     def ruby_shebang?(file)
+      gem_ruby = Gem.ruby.dup
+      gem_ruby.force_encoding('ASCII-8BIT')
       possibilities = [
         "#!/usr/bin/env ruby\n",
         "#!/usr/bin/env jruby\n",
         "#!/usr/bin/env truffleruby\n",
-        "#!#{Gem.ruby}\n",
+        "#!#{gem_ruby}\n",
       ]
 
       if File.zero?(file)