diff --git a/Library/Homebrew/checksum.rb b/Library/Homebrew/checksum.rb
index 506885fce3..c1d0e70551 100644
--- a/Library/Homebrew/checksum.rb
+++ b/Library/Homebrew/checksum.rb
@@ -13,6 +13,6 @@ class Checksum
   delegate [:empty?, :to_s] => :@hexdigest
 
   def ==(other)
-    hash_type == other.hash_type && hexdigest == other.hexdigest
+    hash_type == other&.hash_type && hexdigest == other.hexdigest
   end
 end
diff --git a/Library/Homebrew/test/checksum_spec.rb b/Library/Homebrew/test/checksum_spec.rb
index acab348b7e..01cfd29d13 100644
--- a/Library/Homebrew/test/checksum_spec.rb
+++ b/Library/Homebrew/test/checksum_spec.rb
@@ -15,5 +15,6 @@ describe Checksum do
     it { is_expected.to eq(other) }
     it { is_expected.not_to eq(other_reversed) }
     it { is_expected.not_to eq(other_sha1) }
+    it { is_expected.not_to eq(nil) }
   end
 end