diff --git a/spec/rbnacl/boxes/curve25519xsalsa20poly1305/private_key_spec.rb b/spec/rbnacl/boxes/curve25519xsalsa20poly1305/private_key_spec.rb
index 5fbce3d..94816a9 100644
--- a/spec/rbnacl/boxes/curve25519xsalsa20poly1305/private_key_spec.rb
+++ b/spec/rbnacl/boxes/curve25519xsalsa20poly1305/private_key_spec.rb
@@ -45,13 +45,13 @@
 
   context "#to_bytes" do
     it "returns the bytes of the key" do
-      expect(subject.to_s).to eq bobsk
+      expect(subject.to_bytes).to eq bobsk
     end
   end
 
   context "#to_s" do
     it "returns the raw bytes of the key" do
-      expect(subject.to_bytes).to eq bobsk
+      expect(subject.to_s).to eq bobsk
     end
   end