diff --git a/etcd/Client.hpp b/etcd/Client.hpp
index eb5f143..60e4bad 100644
--- a/etcd/Client.hpp
+++ b/etcd/Client.hpp
@@ -223,7 +223,7 @@ namespace etcd
      * @param value is the new value to be set
      * @param old_index is the expected index of the original value
      */
-    pplx::task<Response> modify_if(std::string const & key, std::string const & value, int old_index, int ttl = 0);
+    pplx::task<Response> modify_if(std::string const & key, std::string const & value, int64_t old_index, int ttl = 0);
 
     /**
      * Modifies an existing key only if it has a specific modification index value. Fails if the key
@@ -233,7 +233,7 @@ namespace etcd
      * @param old_index is the expected index of the original value
      * @param leaseId is the lease attached to the key
      */
-    pplx::task<Response> modify_if(std::string const & key, std::string const & value, int old_index, int64_t leaseId);
+    pplx::task<Response> modify_if(std::string const & key, std::string const & value, int64_t old_index, int64_t leaseId);
 
     /**
      * Removes a single key. The key has to point to a plain, non directory entry.
@@ -254,7 +254,7 @@ namespace etcd
      * @param key is the key to be deleted
      * @param old_index is the expected index of the existing value
      */
-    pplx::task<Response> rm_if(std::string const & key, int old_index);
+    pplx::task<Response> rm_if(std::string const & key, int64_t old_index);
 
     /**
      * Gets a directory listing of the directory identified by the key.
@@ -333,7 +333,7 @@ namespace etcd
      * @param fromIndex the first index we are interested in
      * @param recursive if true watch a whole subtree
      */
-    pplx::task<Response> watch(std::string const & key, int fromIndex, bool recursive = false);
+    pplx::task<Response> watch(std::string const & key, int64_t fromIndex, bool recursive = false);
 
     /**
      * Watches for changes of a range of keys inside [key, range_end).
@@ -362,7 +362,7 @@ namespace etcd
      * @param range_end is the end of key range to be removed.
      * @param fromIndex the first index we are interested in
      */
-    pplx::task<Response> watch(std::string const & key, std::string const &range_end, int fromIndex);
+    pplx::task<Response> watch(std::string const & key, std::string const &range_end, int64_t fromIndex);
 
     /**
      * Grants a lease.
@@ -450,7 +450,7 @@ namespace etcd
      * @param value is the new value to set.
      */
     pplx::task<Response> proclaim(std::string const &name, int64_t lease_id,
-                                  std::string const &key, int revision, std::string const &value);
+                                  std::string const &key, int64_t revision, std::string const &value);
 
     /**
      * Get the current leader proclamation.
@@ -497,7 +497,7 @@ namespace etcd
      * @param revision is the created revision of key-value returned by @campaign@
      */
     pplx::task<Response> resign(std::string const &name, int64_t lease_id,
-                                std::string const &key, int revision);
+                                std::string const &key, int64_t revision);
 
   private:
 #if defined(WITH_GRPC_CHANNEL_CLASS)
diff --git a/etcd/SyncClient.hpp b/etcd/SyncClient.hpp
index e978464..50b3a1e 100644
--- a/etcd/SyncClient.hpp
+++ b/etcd/SyncClient.hpp
@@ -51,11 +51,11 @@ namespace etcd
     Response modify(std::string const & key, std::string const & value, int64_t leaseId);
     Response modify_if(std::string const & key, std::string const & value, std::string const & old_value, int ttl = 0);
     Response modify_if(std::string const & key, std::string const & value, std::string const & old_value, int64_t leaseId);
-    Response modify_if(std::string const & key, std::string const & value, int old_index, int ttl = 0);
-    Response modify_if(std::string const & key, std::string const & value, int old_index, int64_t leaseId);
+    Response modify_if(std::string const & key, std::string const & value, int64_t old_index, int ttl = 0);
+    Response modify_if(std::string const & key, std::string const & value, int64_t old_index, int64_t leaseId);
     Response rm(std::string const & key);
     Response rm_if(std::string const & key, std::string const & old_value);
-    Response rm_if(std::string const & key, int old_index);
+    Response rm_if(std::string const & key, int64_t old_index);
     Response ls(std::string const & key);
     Response ls(std::string const & key, size_t const limit);
     Response ls(std::string const & key, std::string const &range_end);
@@ -71,13 +71,13 @@ namespace etcd
     Response campaign(std::string const &name, int64_t lease_id,
                       std::string const &value);
     Response proclaim(std::string const &name, int64_t lease_id,
-                      std::string const &key, int revision, std::string const &value);
+                      std::string const &key, int64_t revision, std::string const &value);
     Response leader(std::string const &name);
     std::unique_ptr<Client::Observer> observe(std::string const &name,
                                               std::function<void(Response)> callback,
                                               const bool once = false);
     Response resign(std::string const &name, int64_t lease_id,
-                    std::string const &key, int revision);
+                    std::string const &key, int64_t revision);
 
     /**
      * Watches for changes of a key or a subtree. Please note that if you watch e.g. "/testdir" and
@@ -97,8 +97,8 @@ namespace etcd
      * @param fromIndex the first index we are interested in
      * @param recursive if true watch a whole subtree
      */
-    Response watch(std::string const & key, int fromIndex, bool recursive = false);
-    Response watch(std::string const & key, std::string const &range_end, int fromIndex);
+    Response watch(std::string const & key, int64_t fromIndex, bool recursive = false);
+    Response watch(std::string const & key, std::string const &range_end, int64_t fromIndex);
 
   protected:
     Client client;
diff --git a/etcd/v3/Action.hpp b/etcd/v3/Action.hpp
index 46c1785..9c99e41 100644
--- a/etcd/v3/Action.hpp
+++ b/etcd/v3/Action.hpp
@@ -30,8 +30,8 @@ namespace etcdv3
   {
     ActionParameters();
     bool withPrefix;
-    int revision;
-    int old_revision;
+    int64_t revision;
+    int64_t old_revision;
     int64_t lease_id = 0;  // no lease
     int ttl;
     int limit;
diff --git a/src/Client.cpp b/src/Client.cpp
index 7f5a700..15a20ef 100644
--- a/src/Client.cpp
+++ b/src/Client.cpp
@@ -472,7 +472,7 @@ pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std:
   return Response::create(call);
 }
 
-pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, int old_index, int ttl)
+pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, int64_t old_index, int ttl)
 {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
@@ -500,7 +500,7 @@ pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std:
   return Response::create(call);
 }
 
-pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, int old_index, int64_t leaseid)
+pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, int64_t old_index, int64_t leaseid)
 {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
@@ -538,7 +538,7 @@ pplx::task<etcd::Response> etcd::Client::rm_if(std::string const & key, std::str
   return Response::create(call);
 }
 
-pplx::task<etcd::Response> etcd::Client::rm_if(std::string const & key, int old_index)
+pplx::task<etcd::Response> etcd::Client::rm_if(std::string const & key, int64_t old_index)
 {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
@@ -640,7 +640,7 @@ pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, bool rec
   return Response::create(call);
 }
 
-pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, int fromIndex, bool recursive)
+pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, int64_t fromIndex, bool recursive)
 {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
@@ -669,7 +669,7 @@ pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, std::str
   return Response::create(call);
 }
 
-pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, std::string const & range_end, int fromIndex)
+pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, std::string const & range_end, int64_t fromIndex)
 {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
@@ -835,7 +835,7 @@ pplx::task<etcd::Response> etcd::Client::campaign(
 
 pplx::task<etcd::Response> etcd::Client::proclaim(
     std::string const &name, int64_t lease_id,
-    std::string const &key, int revision, std::string const &value) {
+    std::string const &key, int64_t revision, std::string const &value) {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
   params.name = name;
@@ -871,7 +871,7 @@ std::unique_ptr<etcd::Client::Observer> etcd::Client::observe(
 }
 
 pplx::task<etcd::Response> etcd::Client::resign(
-    std::string const &name, int64_t lease_id, std::string const &key, int revision) {
+    std::string const &name, int64_t lease_id, std::string const &key, int64_t revision) {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
   params.name = name;
diff --git a/src/SyncClient.cpp b/src/SyncClient.cpp
index 55c60e3..cd068c3 100644
--- a/src/SyncClient.cpp
+++ b/src/SyncClient.cpp
@@ -78,12 +78,12 @@ etcd::Response etcd::SyncClient::modify_if(std::string const & key, std::string
   CHECK_EXCEPTIONS(client.modify_if(key, value, old_value, leaseId).get());
 }
 
-etcd::Response etcd::SyncClient::modify_if(std::string const & key, std::string const & value, int old_index, int ttl)
+etcd::Response etcd::SyncClient::modify_if(std::string const & key, std::string const & value, int64_t old_index, int ttl)
 {
   CHECK_EXCEPTIONS(client.modify_if(key, value, old_index, ttl).get());
 }
 
-etcd::Response etcd::SyncClient::modify_if(std::string const & key, std::string const & value, int old_index, int64_t leaseId)
+etcd::Response etcd::SyncClient::modify_if(std::string const & key, std::string const & value, int64_t old_index, int64_t leaseId)
 {
   CHECK_EXCEPTIONS(client.modify_if(key, value, old_index, leaseId).get());
 }
@@ -98,7 +98,7 @@ etcd::Response etcd::SyncClient::rm_if(std::string const & key, std::string cons
   CHECK_EXCEPTIONS(client.rm_if(key, old_value).get());
 }
 
-etcd::Response etcd::SyncClient::rm_if(std::string const & key, int old_index)
+etcd::Response etcd::SyncClient::rm_if(std::string const & key, int64_t old_index)
 {
   CHECK_EXCEPTIONS(client.rm_if(key, old_index).get());
 }
@@ -161,7 +161,7 @@ etcd::Response etcd::SyncClient::campaign(std::string const &name, int64_t lease
 }
 
 etcd::Response etcd::SyncClient::proclaim(std::string const &name, int64_t lease_id,
-                                          std::string const &key, int revision,
+                                          std::string const &key, int64_t revision,
                                           std::string const &value)
 {
   CHECK_EXCEPTIONS(client.proclaim(name, lease_id, key, revision, value).get());
@@ -180,7 +180,7 @@ std::unique_ptr<etcd::Client::Observer> etcd::SyncClient::observe(
 }
 
 etcd::Response etcd::SyncClient::resign(std::string const &name, int64_t lease_id,
-                                        std::string const &key, int revision)
+                                        std::string const &key, int64_t revision)
 {
   CHECK_EXCEPTIONS(client.resign(name, lease_id, key, revision).get());
 }
@@ -190,7 +190,7 @@ etcd::Response etcd::SyncClient::watch(std::string const & key, bool recursive)
   CHECK_EXCEPTIONS(client.watch(key, recursive).get());
 }
 
-etcd::Response etcd::SyncClient::watch(std::string const & key, int fromIndex, bool recursive)
+etcd::Response etcd::SyncClient::watch(std::string const & key, int64_t fromIndex, bool recursive)
 {
   CHECK_EXCEPTIONS(client.watch(key, fromIndex, recursive).get());
 }
@@ -205,7 +205,7 @@ etcd::Response etcd::SyncClient::watch(std::string const & key, std::string cons
   CHECK_EXCEPTIONS(client.watch(key, range_end).get());
 }
 
-etcd::Response etcd::SyncClient::watch(std::string const & key, std::string const &range_end, int fromIndex)
+etcd::Response etcd::SyncClient::watch(std::string const & key, std::string const &range_end, int64_t fromIndex)
 {
   CHECK_EXCEPTIONS(client.watch(key, range_end, fromIndex).get());
 }