diff --git a/src/gtest/test_noteencryption.cpp b/src/gtest/test_noteencryption.cpp
index db341d3f4..1aded18f2 100644
--- a/src/gtest/test_noteencryption.cpp
+++ b/src/gtest/test_noteencryption.cpp
@@ -19,7 +19,7 @@ public:
     }
 };
 
-TEST(noteencryption, sapling_api)
+TEST(noteencryption, SaplingApi)
 {
     using namespace libzcash;
 
@@ -44,7 +44,7 @@ TEST(noteencryption, sapling_api)
     }
 
     // Invalid diversifier
-    ASSERT_FALSE(SaplingNoteEncryption::FromDiversifier({1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
+    ASSERT_EQ(boost::none, SaplingNoteEncryption::FromDiversifier({1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
 
     // Encrypt to pk_1
     auto enc = *SaplingNoteEncryption::FromDiversifier(pk_1.d);
diff --git a/src/zcash/NoteEncryption.hpp b/src/zcash/NoteEncryption.hpp
index cee0b21cb..82f8b2abf 100644
--- a/src/zcash/NoteEncryption.hpp
+++ b/src/zcash/NoteEncryption.hpp
@@ -24,6 +24,7 @@ typedef std::array<unsigned char, ZC_SAPLING_ENCPLAINTEXT_SIZE> SaplingEncPlaint
 typedef std::array<unsigned char, ZC_SAPLING_OUTCIPHERTEXT_SIZE> SaplingOutCiphertext;
 typedef std::array<unsigned char, ZC_SAPLING_OUTPLAINTEXT_SIZE> SaplingOutPlaintext;
 
+//! This is not a thread-safe API.
 class SaplingNoteEncryption {
 protected:
     // Ephemeral public key