diff --git a/plugin.go b/plugin.go
index 4cd9f55..f84a406 100644
--- a/plugin.go
+++ b/plugin.go
@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"regexp"
 	"strings"
 	"time"
 
@@ -53,9 +54,7 @@ func (p Plugin) Exec() error {
 
 	var commands []*exec.Cmd
 
-	if len(p.Config.Secrets) != 0 {
-		exportSecrets(p.Config.Secrets)
-	}
+	CopyTfEnv()
 
 	if p.Config.Cacert != "" {
 		commands = append(commands, installCaCert(p.Config.Cacert))
@@ -108,9 +107,14 @@ func installCaCert(cacert string) *exec.Cmd {
 	)
 }
 
-func exportSecrets(secrets map[string]string) {
-	for k, v := range secrets {
-		os.Setenv(fmt.Sprintf("%s", k), fmt.Sprintf("%s", os.Getenv(v)))
+func CopyTfEnv() {
+	tfVar := regexp.MustCompile(`^TF_VAR_.*$`)
+	for _, e := range os.Environ() {
+		pair := strings.Split(e, "=")
+		if tfVar.MatchString(pair[0]) {
+			name := strings.Split(pair[0], "TF_VAR_")
+			os.Setenv(fmt.Sprintf("TF_VAR_%s", strings.ToLower(name[1])), pair[1])
+		}
 	}
 }
 
@@ -187,10 +191,6 @@ func planCommand(config Config) *exec.Cmd {
 		args = append(args, "-var")
 		args = append(args, fmt.Sprintf("%s=%s", k, v))
 	}
-	for k, v := range config.Secrets {
-		args = append(args, "-var")
-		args = append(args, fmt.Sprintf("%s=%s", k, os.Getenv(v)))
-	}
 	if config.Parallelism > 0 {
 		args = append(args, fmt.Sprintf("-parallelism=%d", config.Parallelism))
 	}
diff --git a/plugin_test.go b/plugin_test.go
index d7cc9da..b951d8b 100644
--- a/plugin_test.go
+++ b/plugin_test.go
@@ -1,9 +1,12 @@
 package main
 
 import (
+	"os"
 	"os/exec"
 	"reflect"
 	"testing"
+
+	. "github.com/franela/goblin"
 )
 
 func Test_destroyCommand(t *testing.T) {
@@ -131,3 +134,21 @@ func Test_planCommand(t *testing.T) {
 		})
 	}
 }
+
+func TestPlugin(t *testing.T) {
+	g := Goblin(t)
+
+	g.Describe("CopyTfEnv", func() {
+		g.It("Should create copies of TF_VAR_ to lowercase", func() {
+			// Set some initial TF_VAR_ that are uppercase
+			os.Setenv("TF_VAR_SOMETHING", "some value")
+			os.Setenv("TF_VAR_SOMETHING_ELSE", "some other value")
+
+			CopyTfEnv()
+
+			// Make sure new env vars exist with proper values
+			g.Assert(os.Getenv("TF_VAR_something")).Equal("some value")
+			g.Assert(os.Getenv("TF_VAR_something_else")).Equal("some other value")
+		})
+	})
+}