diff --git a/sdk/instance/instance.go b/sdk/instance/instance.go
index d8ccd602f..ccd64810c 100644
--- a/sdk/instance/instance.go
+++ b/sdk/instance/instance.go
@@ -65,7 +65,7 @@ func (i *Instance) Create(id string, env []string) (*instance.Instance, error) {
 		return nil, err
 	}
 
-	// overwrite default env vars with user defined ones.
+	// calculate the final env vars by overwriting user defined one's with defaults.
 	instanceEnv := xos.EnvMergeMaps(xos.EnvSliceToMap(srv.Configuration.Env), xos.EnvSliceToMap(env))
 
 	// calculate instance's hash.
@@ -92,7 +92,7 @@ func (i *Instance) Create(id string, env []string) (*instance.Instance, error) {
 		return nil, err
 	}
 
-	_, err = i.start(o)
+	_, err = i.start(o, xos.EnvMapToSlice(instanceEnv))
 	return o, err
 }
 
diff --git a/sdk/instance/start.go b/sdk/instance/start.go
index 4d2caa80d..f2aa45cf0 100644
--- a/sdk/instance/start.go
+++ b/sdk/instance/start.go
@@ -11,7 +11,7 @@ import (
 )
 
 // Start starts the service.
-func (i *Instance) start(inst *instance.Instance) (serviceIDs []string, err error) {
+func (i *Instance) start(inst *instance.Instance, env []string) (serviceIDs []string, err error) {
 	srv, err := i.serviceDB.Get(inst.ServiceHash)
 	if err != nil {
 		return nil, err
@@ -55,7 +55,7 @@ func (i *Instance) start(inst *instance.Instance) (serviceIDs []string, err erro
 			Image:   d.Image,
 			Args:    d.Args,
 			Command: d.Command,
-			Env: xos.EnvMergeSlices(d.Env, []string{
+			Env: xos.EnvMergeSlices(env, []string{
 				"MESG_TOKEN=" + inst.Hash,
 				"MESG_ENDPOINT=" + endpoint,
 				"MESG_ENDPOINT_TCP=" + endpoint,