diff --git a/Library/Homebrew/software_spec.rb b/Library/Homebrew/software_spec.rb
index dc7fdfbfa4..c27f124aa6 100644
--- a/Library/Homebrew/software_spec.rb
+++ b/Library/Homebrew/software_spec.rb
@@ -205,6 +205,8 @@ class SoftwareSpec
 
   def patch(strip = :p1, src = nil, &block)
     p = Patch.create(strip, src, &block)
+    return if p.is_a?(ExternalPatch) && p.url.blank?
+
     dependency_collector.add(p.resource) if p.is_a? ExternalPatch
     patches << p
   end
diff --git a/Library/Homebrew/test/software_spec_spec.rb b/Library/Homebrew/test/software_spec_spec.rb
index 24b50bb8da..284cf2211a 100644
--- a/Library/Homebrew/test/software_spec_spec.rb
+++ b/Library/Homebrew/test/software_spec_spec.rb
@@ -171,5 +171,12 @@ describe SoftwareSpec do
       expect(spec.patches.count).to eq(1)
       expect(spec.patches.first.strip).to eq(:p1)
     end
+
+    it "doesn't add a patch with no url" do
+      spec.patch do
+        sha256 "7852a7a365f518b12a1afd763a6a80ece88ac7aeea3c9023aa6c1fe46ac5a1ae"
+      end
+      expect(spec.patches.empty?).to be true
+    end
   end
 end