diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 6b8330f231..0743c6e031 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -1044,6 +1044,7 @@ module Homebrew
       end
 
       def check_for_autoconf
+        return unless MacOS::Xcode.installed?
         return unless MacOS::Xcode.provides_autotools?
 
         autoconf = which("autoconf")
diff --git a/Library/Homebrew/test/test_diagnostic.rb b/Library/Homebrew/test/test_diagnostic.rb
index 8aa2c6f674..07bae8329e 100644
--- a/Library/Homebrew/test/test_diagnostic.rb
+++ b/Library/Homebrew/test/test_diagnostic.rb
@@ -205,6 +205,7 @@ class DiagnosticChecksTest < Homebrew::TestCase
   end
 
   def test_check_for_autoconf
+    MacOS::Xcode.stubs(:installed?).returns true
     MacOS::Xcode.stubs(:provides_autotools?).returns true
     mktmpdir do |path|
       file = "#{path}/autoconf"