diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 6922430e81..38ecf30bf0 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -419,7 +419,7 @@ class FormulaInstaller
   end
 
   def build_time
-    @build_time ||= Time.now - @start_time unless interactive? or @start_time.nil?
+    @build_time ||= Time.now - @start_time if @start_time && !interactive?
   end
 
   def sanitized_ARGV_options