diff --git a/env.go b/env.go
index 389cb1b..f6c7a4f 100644
--- a/env.go
+++ b/env.go
@@ -7,6 +7,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/imdario/mergo"
 	"github.com/unistack-org/micro/v3/config"
 )
 
@@ -36,9 +37,15 @@ func (c *envConfig) Load(ctx context.Context) error {
 		}
 	}
 
-	valueOf := reflect.ValueOf(c.opts.Struct)
+	dst, err := config.Zero(c.opts.Struct)
+	if err == nil {
+		err = c.fillValues(ctx, reflect.ValueOf(dst))
+	}
+	if err != nil && !c.opts.AllowFail {
+		return err
+	}
 
-	if err := c.fillValues(ctx, valueOf); err != nil && !c.opts.AllowFail {
+	if err = mergo.Merge(c.opts.Struct, dst, mergo.WithOverride, mergo.WithTypeCheck, mergo.WithAppendSlice); err != nil && !c.opts.AllowFail {
 		return err
 	}
 
diff --git a/env_test.go b/env_test.go
index 7f30dae..dbea796 100644
--- a/env_test.go
+++ b/env_test.go
@@ -1,20 +1,21 @@
 package env_test
 
 import (
-	"github.com/unistack-org/micro/v3/config"
-	env	"github.com/unistack-org/micro-config-env"
-	"testing"
 	"context"
 	"os"
+	"testing"
+
+	env "github.com/unistack-org/micro-config-env"
+	"github.com/unistack-org/micro/v3/config"
 )
 
 type Config struct {
-	StringValue string `env:"STRING_VALUE"`
-	BoolValue bool `env:"BOOL_VALUE"`
-	StringSlice []string `env:"STRING_SLICE"`
-	IntSlice []int `env:"INT_SLICE"`
+	StringValue    string            `env:"STRING_VALUE"`
+	BoolValue      bool              `env:"BOOL_VALUE"`
+	StringSlice    []string          `env:"STRING_SLICE"`
+	IntSlice       []int             `env:"INT_SLICE"`
 	MapStringValue map[string]string `env:"MAP_STRING"`
-	MapIntValue map[string]int `env:"MAP_INT"`
+	MapIntValue    map[string]int    `env:"MAP_INT"`
 }
 
 func TestEnv(t *testing.T) {
@@ -26,43 +27,43 @@ func TestEnv(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := cfg.Load(ctx); err !=nil {
+	if err := cfg.Load(ctx); err != nil {
 		t.Fatal(err)
 	}
 
 	if conf.StringValue != "before_load" {
-		t.Fatalf("something wrong with env config: %v", conf)
+		t.Fatalf("something wrong with env config: %#+v", conf)
 	}
 
-
-	os.Setenv("STRING_VALUE","STRING_VALUE")
-	os.Setenv("BOOL_VALUE","true")
+	os.Setenv("STRING_VALUE", "STRING_VALUE")
+	os.Setenv("BOOL_VALUE", "true")
 	os.Setenv("STRING_SLICE", "STRING_SLICE1,STRING_SLICE2;STRING_SLICE3")
 	os.Setenv("INT_SLICE", "1,2,3,4,5")
 	os.Setenv("MAP_STRING", "key1=val1,key2=val2")
 	os.Setenv("MAP_INT", "key1=1,key2=2")
 
-	if err := cfg.Load(ctx); err !=nil {
+	if err := cfg.Load(ctx); err != nil {
 		t.Fatal(err)
 	}
 	if conf.StringValue != "STRING_VALUE" {
-		t.Fatalf("something wrong with env config: %v", conf)
+		t.Fatalf("something wrong with env config: %#+v", conf)
 	}
 
 	if !conf.BoolValue {
-		t.Fatalf("something wrong with env config: %v", conf)
+		t.Fatalf("something wrong with env config: %#+v", conf)
 	}
 
 	if len(conf.StringSlice) != 3 {
-		t.Fatalf("something wrong with env config: %v", conf)
+		t.Fatalf("something wrong with env config: %#+v", conf.StringSlice)
 	}
 
 	if len(conf.MapStringValue) != 2 {
-		t.Fatalf("something wrong with env config: %v", conf)
+		t.Fatalf("something wrong with env config: %#+v", conf.MapStringValue)
 	}
 
 	if len(conf.MapIntValue) != 2 {
-		t.Fatalf("something wrong with env config: %v", conf)
+		t.Fatalf("something wrong with env config: %#+v", conf.MapIntValue)
 	}
 
+	t.Logf("cfg %#+v", conf)
 }
diff --git a/go.mod b/go.mod
index 9333506..1dce4ad 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module github.com/unistack-org/micro-config-env
 
 go 1.15
 
-require github.com/unistack-org/micro/v3 v3.0.2-0.20201219202205-150e8ad698bb
+require (
+	github.com/imdario/mergo v0.3.11
+	github.com/unistack-org/micro/v3 v3.0.2-0.20201219211529-b50855855b58
+)
diff --git a/go.sum b/go.sum
index 8bca64c..0412e8e 100644
--- a/go.sum
+++ b/go.sum
@@ -134,6 +134,8 @@ github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ
 github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/iij/doapi v0.0.0-20190504054126-0bbf12d6d7df/go.mod h1:QMZY7/J/KSQEhKWFeDesPjMj+wCHReeknARU3wqlyN4=
+github.com/imdario/mergo v0.3.11 h1:3tnifQM4i+fbajXKBHXWEH+KvNHqojZ778UH75j3bGA=
+github.com/imdario/mergo v0.3.11/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
 github.com/jmespath/go-jmespath v0.0.0-20180206201540-c2b33e8439af/go.mod h1:Nht3zPeWKUH0NzdCt2Blrr5ys8VGpn0CEB0cQHVjt7k=
 github.com/json-iterator/go v1.1.5/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
 github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
@@ -235,10 +237,8 @@ github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5
 github.com/timewasted/linode v0.0.0-20160829202747-37e84520dcf7/go.mod h1:imsgLplxEC/etjIhdr3dNzV3JeT27LbVu5pYWm0JCBY=
 github.com/transip/gotransip v0.0.0-20190812104329-6d8d9179b66f/go.mod h1:i0f4R4o2HM0m3DZYQWsj6/MEowD57VzoH0v3d7igeFY=
 github.com/uber-go/atomic v1.3.2/go.mod h1:/Ct5t2lcmbJ4OSe/waGBoaVvVqtO0bmtfVNex1PFV8g=
-github.com/unistack-org/micro/v3 v3.0.2-0.20201213101738-2dcd30b21c0f h1:VTnea0NAgE0LXQNBpiemP/O6G0Uns6sl5KkyeAKodEU=
-github.com/unistack-org/micro/v3 v3.0.2-0.20201213101738-2dcd30b21c0f/go.mod h1:0DgOy4OdJxQCDER8YSKitZugd2+1bddrRSNfeooTHDc=
-github.com/unistack-org/micro/v3 v3.0.2-0.20201219202205-150e8ad698bb h1:cJGF8j30idReDyjRCvEJN5waWCh/AKuiKEqLA8OLMlY=
-github.com/unistack-org/micro/v3 v3.0.2-0.20201219202205-150e8ad698bb/go.mod h1:0DgOy4OdJxQCDER8YSKitZugd2+1bddrRSNfeooTHDc=
+github.com/unistack-org/micro/v3 v3.0.2-0.20201219211529-b50855855b58 h1:cxBL1qxHsugjajAf/N14Lmk8V1KL1LH9rMGnYEokrpI=
+github.com/unistack-org/micro/v3 v3.0.2-0.20201219211529-b50855855b58/go.mod h1:0DgOy4OdJxQCDER8YSKitZugd2+1bddrRSNfeooTHDc=
 github.com/urfave/cli v1.22.1/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
 github.com/vultr/govultr v0.1.4/go.mod h1:9H008Uxr/C4vFNGLqKx232C206GL0PBHzOP0809bGNA=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f/go.mod h1:N2zxlSyiKSe5eX1tZViRH5QA0qijqEDrYZiPEAiq3wU=