diff --git a/go.mod b/go.mod
index 516bad3..a551d60 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,7 @@ require (
 	github.com/franela/goblin v0.0.0-20170111051028-2fa789fd0c6b
 	github.com/go-ini/ini v1.21.1
 	github.com/jmespath/go-jmespath v0.0.0-20160803190731-bd40a432e4c7
-	github.com/joho/godotenv v0.0.0-20150907010228-4ed13390c0ac
+	github.com/joho/godotenv v1.3.0
 	github.com/urfave/cli v0.0.0-20161006035353-55f715e28c46
 	golang.org/x/sys v0.0.0-20161006025142-8d1157a43547
 )
diff --git a/go.sum b/go.sum
index 36769c9..c79449a 100644
--- a/go.sum
+++ b/go.sum
@@ -10,6 +10,8 @@ github.com/jmespath/go-jmespath v0.0.0-20160803190731-bd40a432e4c7 h1:SMvOWPJCES
 github.com/jmespath/go-jmespath v0.0.0-20160803190731-bd40a432e4c7/go.mod h1:Nht3zPeWKUH0NzdCt2Blrr5ys8VGpn0CEB0cQHVjt7k=
 github.com/joho/godotenv v0.0.0-20150907010228-4ed13390c0ac h1:wF2VgtpbaLqhBHV9FxVWzgzgv8VcCjZ66Bl/+F6cpT0=
 github.com/joho/godotenv v0.0.0-20150907010228-4ed13390c0ac/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
+github.com/joho/godotenv v1.3.0 h1:Zjp+RcGpHhGlrMbJzXTrZZPrWj+1vfm90La1wgB6Bhc=
+github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
 github.com/urfave/cli v0.0.0-20161006035353-55f715e28c46 h1:EztUvugq7AA7F3lYLmtFQyvKdcY5pisPt10DqPjRCL8=
 github.com/urfave/cli v0.0.0-20161006035353-55f715e28c46/go.mod h1:70zkFmudgCuE/ngEzBv17Jvp/497gISqfk5gWijbERA=
 golang.org/x/sys v0.0.0-20161006025142-8d1157a43547/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
diff --git a/main.go b/main.go
index 7f230b0..7778723 100644
--- a/main.go
+++ b/main.go
@@ -35,8 +35,9 @@ func main() {
 			EnvVar: "PLUGIN_CA_CERT",
 		},
 		cli.StringFlag{
-			Name:  "env-file",
-			Usage: "source env file",
+			Name:   "env_file",
+			Usage:  "pass filename to source it and load variables into current shell",
+			EnvVar: "PLUGIN_ENV_FILE",
 		},
 		cli.StringFlag{
 			Name:   "init_options",
@@ -125,8 +126,8 @@ func run(c *cli.Context) error {
 		"Revision": revision,
 	}).Info("Drone Terraform Plugin Version")
 
-	if c.String("env-file") != "" {
-		_ = godotenv.Load(c.String("env-file"))
+	if c.String("env_file") != "" {
+		_ = godotenv.Load(c.String("env_file"))
 	}
 
 	var vars map[string]string
diff --git a/plugin.go b/plugin.go
index 07dfaa0..66a36ca 100644
--- a/plugin.go
+++ b/plugin.go
@@ -77,7 +77,7 @@ func (p Plugin) Exec() error {
 		}
 	}
 
-	if p.Config.RoleARN != "" {
+	if p.Config.RoleARN != "" && !credsSet() {
 		assumeRole(p.Config.RoleARN)
 	}
 
@@ -169,6 +169,16 @@ func CopyTfEnv() {
 	}
 }
 
+func credsSet() bool {
+	awsTokens := []string{"AWS_ACCESS_KEY_ID", "AWS_SECRET_ACCESS_KEY", "AWS_SESSION_TOKEN"}
+	for _, token := range awsTokens {
+		if os.Getenv(token) == "" {
+			return false
+		}
+	}
+	return true
+}
+
 func assumeRole(roleArn string) {
 	client := sts.New(session.New())
 	duration := time.Hour * 1
diff --git a/plugin_test.go b/plugin_test.go
index a131f11..23487a9 100644
--- a/plugin_test.go
+++ b/plugin_test.go
@@ -27,6 +27,44 @@ func TestPlugin(t *testing.T) {
 		})
 	})
 
+	g.Describe("credsSet", func() {
+		tests := []struct {
+			name string
+			args map[string]string
+			want bool
+		}{
+			{
+				"Should return true when all credentials were set",
+				map[string]string{"AWS_ACCESS_KEY_ID": "x", "AWS_SECRET_ACCESS_KEY": "x", "AWS_SESSION_TOKEN": "x"},
+				true,
+			},
+			{
+				"Should return false when access key id is missing",
+				map[string]string{"AWS_SECRET_ACCESS_KEY": "x", "AWS_SESSION_TOKEN": "x"},
+				false,
+			},
+			{
+				"Should return false when secret access key is missing",
+				map[string]string{"AWS_ACCESS_KEY_ID": "x", "AWS_SESSION_TOKEN": "x"},
+				false,
+			},
+			{
+				"Should return false when session token is missing",
+				map[string]string{"AWS_ACCESS_KEY_ID": "x", "AWS_SECRET_ACCESS_KEY": "x"},
+				false,
+			},
+		}
+
+		for _, tt := range tests {
+			g.It(tt.name, func() {
+				for k, v := range tt.args {
+					os.Setenv(k, v)
+				}
+				g.Assert(credsSet()).Equal(tt.want)
+			})
+		}
+	})
+
 	g.Describe("tfApply", func() {
 		g.It("Should return correct apply commands given the arguments", func() {
 			type args struct {