diff --git a/src/crypto/aes.cpp b/src/crypto/aes.cpp
index 09db92b..2dbae6c 100644
--- a/src/crypto/aes.cpp
+++ b/src/crypto/aes.cpp
@@ -29,7 +29,8 @@ struct aes_encoder::impl
 
 aes_encoder::aes_encoder()
 {
-  static __attribute__((unused)) int init = init_openssl();
+  static int init = init_openssl();
+  (void)init;
 }
 
 aes_encoder::~aes_encoder()
@@ -97,7 +98,8 @@ struct aes_decoder::impl
 
 aes_decoder::aes_decoder()
 {
-  static __attribute__((unused)) int init = init_openssl();
+  static int init = init_openssl();
+  (void)init;
 }
 
 void aes_decoder::init( const fc::sha256& key, const fc::uint128& init_value )
diff --git a/src/crypto/elliptic_secp256k1.cpp b/src/crypto/elliptic_secp256k1.cpp
index 469cc1b..ecb2c0c 100644
--- a/src/crypto/elliptic_secp256k1.cpp
+++ b/src/crypto/elliptic_secp256k1.cpp
@@ -29,8 +29,10 @@ namespace fc { namespace ecc {
         }
 
         void _init_lib() {
-            static __attribute__((unused)) const secp256k1_context_t* ctx = _get_context();
-            static __attribute__((unused)) int init_o = init_openssl();
+            static const secp256k1_context_t* ctx = _get_context();
+            (void)ctx;
+            static int init_o = init_openssl();
+            (void)init_o;
         }
 
         class public_key_impl
diff --git a/src/crypto/rand.cpp b/src/crypto/rand.cpp
index 2b194c5..6b26b46 100644
--- a/src/crypto/rand.cpp
+++ b/src/crypto/rand.cpp
@@ -8,7 +8,8 @@ namespace fc {
 
 void rand_bytes(char* buf, int count)
 {
-  static __attribute__((unused)) int init = init_openssl();
+  static int init = init_openssl();
+  (void)init;
 
   int result = RAND_bytes((unsigned char*)buf, count);
   if (result != 1)
@@ -17,7 +18,8 @@ void rand_bytes(char* buf, int count)
 
 void rand_pseudo_bytes(char* buf, int count)
 {
-  static __attribute__((unused)) int init = init_openssl();
+  static int init = init_openssl();
+  (void)init;
 
   int result = RAND_pseudo_bytes((unsigned char*)buf, count);
   if (result == -1)