diff --git a/Library/Homebrew/pkg_version.rb b/Library/Homebrew/pkg_version.rb
index 43b45d60eb..b08536bfa0 100644
--- a/Library/Homebrew/pkg_version.rb
+++ b/Library/Homebrew/pkg_version.rb
@@ -36,7 +36,10 @@ class PkgVersion
   def <=>(other)
     return unless other.is_a?(PkgVersion)
 
-    (version <=> other.version).nonzero? || revision <=> other.revision
+    comp_ver = (version <=> other.version)
+    return if comp_ver.nil?
+
+    comp_ver.nonzero? || revision <=> other.revision
   end
   alias eql? ==
 
diff --git a/Library/Homebrew/test/pkg_version_spec.rb b/Library/Homebrew/test/pkg_version_spec.rb
index 8e456ad623..474485ffe3 100644
--- a/Library/Homebrew/test/pkg_version_spec.rb
+++ b/Library/Homebrew/test/pkg_version_spec.rb
@@ -54,6 +54,11 @@ describe PkgVersion do
   describe "#<=>" do
     it "returns nil if the comparison fails" do
       expect(described_class.new(Version.create("1.0"), 0) <=> Object.new).to be nil
+      expect(Object.new <=> described_class.new(Version.create("1.0"), 0)).to be nil
+      expect(Object.new <=> described_class.new(Version.create("1.0"), 0)).to be nil
+      expect(described_class.new(Version.create("1.0"), 0) <=> nil).to be nil
+      # This one used to fail due to dereferencing a null `self`
+      expect(described_class.new(nil, 0) <=> described_class.new(Version.create("1.0"), 0)).to be nil
     end
   end