diff --git a/include/fc/array.hpp b/include/fc/array.hpp
index cae423f..b465b59 100644
--- a/include/fc/array.hpp
+++ b/include/fc/array.hpp
@@ -117,8 +117,6 @@ namespace fc {
 #include <fc/crypto/city.hpp>
 namespace std
 {
-    template<typename T> struct hash;
-
     template<typename T, size_t N>
     struct hash<fc::array<T,N> >
     {
diff --git a/include/fc/crypto/ripemd160.hpp b/include/fc/crypto/ripemd160.hpp
index 9816fe4..5cf404d 100644
--- a/include/fc/crypto/ripemd160.hpp
+++ b/include/fc/crypto/ripemd160.hpp
@@ -79,8 +79,6 @@ class ripemd160
 
 namespace std
 {
-    template<typename T> struct hash;
-
     template<>
     struct hash<fc::ripemd160>
     {
diff --git a/include/fc/crypto/sha1.hpp b/include/fc/crypto/sha1.hpp
index 991ae57..62d077c 100644
--- a/include/fc/crypto/sha1.hpp
+++ b/include/fc/crypto/sha1.hpp
@@ -72,8 +72,6 @@ class sha1
 
 namespace std
 {
-    template<typename T> struct hash;
-
     template<>
     struct hash<fc::sha1>
     {
diff --git a/include/fc/crypto/sha224.hpp b/include/fc/crypto/sha224.hpp
index 26fd51b..a7ed1ae 100644
--- a/include/fc/crypto/sha224.hpp
+++ b/include/fc/crypto/sha224.hpp
@@ -73,8 +73,6 @@ class sha224
 } // fc
 namespace std
 {
-    template<typename T> struct hash;
-
     template<>
     struct hash<fc::sha224>
     {
diff --git a/include/fc/network/ip.hpp b/include/fc/network/ip.hpp
index 900c89a..60b95d7 100644
--- a/include/fc/network/ip.hpp
+++ b/include/fc/network/ip.hpp
@@ -112,8 +112,6 @@ namespace fc {
 }
 namespace std
 {
-    template<typename T> struct hash;
-
     template<>
     struct hash<fc::ip::endpoint>
     {
diff --git a/include/fc/uint128.hpp b/include/fc/uint128.hpp
index 2d84c4f..d41b388 100644
--- a/include/fc/uint128.hpp
+++ b/include/fc/uint128.hpp
@@ -99,8 +99,6 @@ namespace fc
 
 namespace std
 {
-    template<typename T> struct hash;
-
     template<>
     struct hash<fc::uint128>
     {