diff --git a/arg.go b/arg.go
index 63364ec..1759685 100644
--- a/arg.go
+++ b/arg.go
@@ -3,6 +3,7 @@ package args
 import (
 	"fmt"
 	"strconv"
+	"strings"
 	"time"
 )
 
@@ -17,8 +18,8 @@ type Arg struct {
 
 func NewArg(argType Type, key, help string, def interface{}) *Arg {
 	return &Arg{
-		Env:     key,
-		Flag:    key,
+		Env:     strings.ToUpper(key),
+		Flag:    strings.ToLower(key),
 		Help:    help,
 		Default: def,
 		Value:   def,
diff --git a/argset_test.go b/argset_test.go
index d51ac22..a7005eb 100644
--- a/argset_test.go
+++ b/argset_test.go
@@ -22,19 +22,19 @@ func TestParse(t *testing.T) {
 	defer func() {
 		os.Args = osArgs
 	}()
-	os.Args = []string{"nothing", "-testkeyFlag", "5"}
-	os.Setenv("testkeyEnv", "9")
+	os.Args = []string{"nothing", "-flag", "5"}
+	os.Setenv("ENV", "9")
 	as := NewArgSet()
-	as.Append(INT, "testkeyFlag", "help", 1)
-	as.Append(INT, "testkeyEnv", "help", 2)
-	as.Append(INT, "testkeyDefault", "help", 3)
+	as.Append(INT, "flag", "help", 1)
+	as.Append(INT, "env", "help", 2)
+	as.Append(INT, "default", "help", 3)
 	if err := as.Parse(); err != nil {
 		t.Fatalf("cannot parse legal: %v", err)
-	} else if arg := as.Get("testkeyFlag"); arg == nil || arg.Value != 5 {
+	} else if arg := as.Get("flag"); arg == nil || arg.Value != 5 {
 		t.Errorf("cannot set from flag: got %v", arg)
-	} else if arg := as.Get("testkeyEnv"); arg == nil || arg.Value != 9 {
+	} else if arg := as.Get("env"); arg == nil || arg.Value != 9 {
 		t.Errorf("cannot set from env: got %v", arg)
-	} else if arg := as.Get("testkeyDefault"); arg == nil || arg.Value != 3 {
+	} else if arg := as.Get("default"); arg == nil || arg.Value != 3 {
 		t.Errorf("cannot set from default: got %v", arg)
 	}