diff --git a/src/bls.cpp b/src/bls.cpp
index 7586e549b..17e8e4c1f 100644
--- a/src/bls.cpp
+++ b/src/bls.cpp
@@ -20,6 +20,8 @@
 
 namespace bls {
 
+const size_t BLS::MESSAGE_HASH_LEN;
+
 bool BLSInitResult = BLS::Init();
 
 Util::SecureAllocCallback Util::secureAllocCallback;
diff --git a/src/elements.cpp b/src/elements.cpp
index 39861f6ec..63405a682 100644
--- a/src/elements.cpp
+++ b/src/elements.cpp
@@ -19,6 +19,8 @@
 
 namespace bls {
 
+const size_t G1Element::SIZE;
+
 G1Element G1Element::FromBytes(const Bytes& bytes, bool fLegacy)
 {
     if (bytes.size() != SIZE) {
@@ -214,7 +216,9 @@ G1Element operator*(const bn_t& k, const G1Element& a) { return a * k; }
 
 
 
-G2Element G2Element::FromBytes(const Bytes& bytes, const bool fLegacy)
+const size_t G2Element::SIZE;
+
+G2Element G2Element::FromBytes(const Bytes& bytes, bool fLegacy)
 {
     if (bytes.size() != SIZE) {
         throw std::invalid_argument("G2Element::FromBytes: Invalid size");
@@ -429,6 +433,8 @@ G2Element operator*(const bn_t& k, const G2Element& a) { return a * k; }
 
 // GTElement
 
+const size_t GTElement::SIZE;
+
 GTElement GTElement::FromBytes(const Bytes& bytes)
 {
     if (bytes.size() != SIZE) {
diff --git a/src/privatekey.cpp b/src/privatekey.cpp
index bfd296d7b..182d7781b 100644
--- a/src/privatekey.cpp
+++ b/src/privatekey.cpp
@@ -17,6 +17,8 @@
 
 namespace bls {
 
+const size_t PrivateKey::PRIVATE_KEY_SIZE;
+
 // Construct a private key from a bytearray.
 PrivateKey PrivateKey::FromBytes(const Bytes& bytes, bool modOrder)
 {