diff --git a/examples/README.md b/examples/README.md
index f2ec29c..150fd39 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -75,7 +75,7 @@
 
 type uppercaseResponse struct {
 	V   string `json:"v"`
-	Err string `json:"err"` // errors don't define JSON marshaling
+	Err string `json:"err,omitempty"` // errors don't define JSON marshaling
 }
 
 type countRequest struct {
diff --git a/examples/stringsvc1/main.go b/examples/stringsvc1/main.go
index ea4e5b8..f33125c 100644
--- a/examples/stringsvc1/main.go
+++ b/examples/stringsvc1/main.go
@@ -59,7 +59,10 @@
 	return func(ctx context.Context, request interface{}) (interface{}, error) {
 		req := request.(uppercaseRequest)
 		v, err := svc.Uppercase(req.S)
-		return uppercaseResponse{v, err.Error()}, nil
+		if err != nil {
+			return uppercaseResponse{v, err.Error()}, nil
+		}
+		return uppercaseResponse{v, ""}, nil
 	}
 }
 
@@ -97,7 +100,7 @@
 
 type uppercaseResponse struct {
 	V   string `json:"v"`
-	Err string `json:"err"` // errors don't define JSON marshaling
+	Err string `json:"err,omitempty"` // errors don't define JSON marshaling
 }
 
 type countRequest struct {
diff --git a/examples/stringsvc2/transport.go b/examples/stringsvc2/transport.go
index 080cf0d..0c29140 100644
--- a/examples/stringsvc2/transport.go
+++ b/examples/stringsvc2/transport.go
@@ -13,7 +13,10 @@
 	return func(ctx context.Context, request interface{}) (interface{}, error) {
 		req := request.(uppercaseRequest)
 		v, err := svc.Uppercase(req.S)
-		return uppercaseResponse{v, err.Error()}, nil
+		if err != nil {
+			return uppercaseResponse{v, err.Error()}, nil
+		}
+		return uppercaseResponse{v, ""}, nil
 	}
 }
 
@@ -51,7 +54,7 @@
 
 type uppercaseResponse struct {
 	V   string `json:"v"`
-	Err string `json:"err"`
+	Err string `json:"err,omitempty"`
 }
 
 type countRequest struct {
diff --git a/examples/stringsvc3/transport.go b/examples/stringsvc3/transport.go
index cb5c4e9..b6d3dfb 100644
--- a/examples/stringsvc3/transport.go
+++ b/examples/stringsvc3/transport.go
@@ -15,7 +15,10 @@
 	return func(ctx context.Context, request interface{}) (interface{}, error) {
 		req := request.(uppercaseRequest)
 		v, err := svc.Uppercase(req.S)
-		return uppercaseResponse{v, err.Error()}, nil
+		if err != nil {
+			return uppercaseResponse{v, err.Error()}, nil
+		}
+		return uppercaseResponse{v, ""}, nil
 	}
 }
 
@@ -70,7 +73,7 @@
 
 type uppercaseResponse struct {
 	V   string `json:"v"`
-	Err string `json:"err"`
+	Err string `json:"err,omitempty"`
 }
 
 type countRequest struct {