diff --git a/poly1305.cpp b/poly1305.cpp
index f580fc42..9bef7585 100644
--- a/poly1305.cpp
+++ b/poly1305.cpp
@@ -33,13 +33,13 @@ void Poly1305_Base<T>::UncheckedSetKey(const byte *key, unsigned int length, con
 	ConstByteArrayParameter t;
 	if (params.GetValue(Name::IV(), t) && t.begin() && t.size())
 	{
-		SecByteBlock nk(16);
-		m_cipher.ProcessBlock(t.begin(), nk);
+		// Nonce key is a class member to avoid the zeroizer on a temporary
+		m_cipher.ProcessBlock(t.begin(), m_nk.begin());
 
-		m_n[0] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, nk +  0);
-		m_n[1] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, nk +  4);
-		m_n[2] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, nk +  8);
-		m_n[3] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, nk + 12);
+		m_n[0] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, m_nk +  0);
+		m_n[1] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, m_nk +  4);
+		m_n[2] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, m_nk +  8);
+		m_n[3] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, m_nk + 12);
 
 		m_used = false;
 	}
diff --git a/poly1305.h b/poly1305.h
index 2e70dcf3..8e2617d0 100644
--- a/poly1305.h
+++ b/poly1305.h
@@ -93,7 +93,7 @@ protected:
 	FixedSizeAlignedSecBlock<word32, 4> m_n;
 
 	// Accumulated message bytes and index
-	FixedSizeAlignedSecBlock<byte, BLOCKSIZE> m_acc;
+	FixedSizeAlignedSecBlock<byte, BLOCKSIZE> m_acc, m_nk;
 	size_t m_idx;
 
 	// Track nonce reuse; assert in debug but continue