diff --git a/Library/Homebrew/utils/pypi.rb b/Library/Homebrew/utils/pypi.rb
index 54ff4fd551..42f4a8727c 100644
--- a/Library/Homebrew/utils/pypi.rb
+++ b/Library/Homebrew/utils/pypi.rb
@@ -307,6 +307,7 @@ module PyPI
     found_packages.sort.each do |package|
       if exclude_packages.include? package
         ohai "Excluding \"#{package}\"" if show_info
+        exclude_packages.delete package
         next
       end
 
@@ -332,6 +333,8 @@ module PyPI
       EOS
     end
 
+    odie "Excluded superfluous packages: #{exclude_packages.join(", ")}" if exclude_packages.any?
+
     if print_only
       puts new_resource_blocks.chomp
       return