diff --git a/client/grpc_client.go b/client/grpc_client.go
index 524f1f7f9..c7a4c2aed 100644
--- a/client/grpc_client.go
+++ b/client/grpc_client.go
@@ -13,6 +13,8 @@ import (
 	cmn "github.com/tendermint/tmlibs/common"
 )
 
+var _ Client = (*grpcClient)(nil)
+
 // A stripped copy of the remoteClient that makes
 // synchronous calls using grpc
 type grpcClient struct {
diff --git a/client/local_client.go b/client/local_client.go
index 9081406af..2a294f48a 100644
--- a/client/local_client.go
+++ b/client/local_client.go
@@ -7,6 +7,8 @@ import (
 	cmn "github.com/tendermint/tmlibs/common"
 )
 
+var _ Client = (*localClient)(nil)
+
 type localClient struct {
 	cmn.BaseService
 	mtx *sync.Mutex
diff --git a/client/socket_client.go b/client/socket_client.go
index ef0a6ecea..642119792 100644
--- a/client/socket_client.go
+++ b/client/socket_client.go
@@ -23,6 +23,8 @@ const reqQueueSize = 256 // TODO make configurable
 // const maxResponseSize = 1048576 // 1MB TODO make configurable
 const flushThrottleMS = 20 // Don't wait longer than...
 
+var _ Client = (*socketClient)(nil)
+
 // This is goroutine-safe, but users should beware that
 // the application in general is not meant to be interfaced
 // with concurrent callers.