diff --git a/lib/config.go b/lib/config.go
index d889364..67f9ec0 100644
--- a/lib/config.go
+++ b/lib/config.go
@@ -11,6 +11,10 @@ import (
 )
 
 const (
+	DefaultScope     = "/"
+	DefaultModify    = false
+	DefaultDebug     = false
+	DefaultNoSniff   = false
 	DefaultTLS       = false
 	DefaultAuth      = false
 	DefaultCert      = "cert.pem"
@@ -65,8 +69,15 @@ func ParseConfig(filename string, flags *pflag.FlagSet) (*Config, error) {
 	v.SetEnvPrefix("wd")
 	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
 	v.AutomaticEnv()
+	// TODO: use new env struct bind feature when it's released in viper.
+	// This should make it redundant to set defaults for things that are
+	// empty or false.
 
 	// Defaults shared with flags
+	v.SetDefault("Scope", DefaultScope)
+	v.SetDefault("Modify", DefaultModify)
+	v.SetDefault("Debug", DefaultDebug)
+	v.SetDefault("NoSniff", DefaultNoSniff)
 	v.SetDefault("TLS", DefaultTLS)
 	v.SetDefault("Cert", DefaultCert)
 	v.SetDefault("Key", DefaultKey)
diff --git a/lib/config_test.go b/lib/config_test.go
index 1c688a3..a16394d 100644
--- a/lib/config_test.go
+++ b/lib/config_test.go
@@ -5,6 +5,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -195,3 +196,24 @@ rules:
 	require.NotEmpty(t, cfg.Rules[1].Path)
 	require.Nil(t, cfg.Rules[1].Regexp)
 }
+
+func TestConfigEnv(t *testing.T) {
+	require.NoError(t, os.Setenv("WD_PORT", "1234"))
+	require.NoError(t, os.Setenv("WD_DEBUG", "true"))
+	require.NoError(t, os.Setenv("WD_MODIFY", "true"))
+	require.NoError(t, os.Setenv("WD_SCOPE", "/test"))
+
+	cfg, err := ParseConfig("", nil)
+	require.NoError(t, err)
+
+	assert.Equal(t, 1234, cfg.Port)
+	assert.Equal(t, "/test", cfg.Scope)
+	assert.Equal(t, true, cfg.Debug)
+	assert.Equal(t, true, cfg.Modify)
+
+	// Reset
+	require.NoError(t, os.Setenv("WD_PORT", ""))
+	require.NoError(t, os.Setenv("WD_DEBUG", ""))
+	require.NoError(t, os.Setenv("WD_MODIFY", ""))
+	require.NoError(t, os.Setenv("WD_SCOPE", ""))
+}