diff --git a/stats/csv/config.go b/stats/csv/config.go
index 95a7a2b33be..87b5f626ae0 100644
--- a/stats/csv/config.go
+++ b/stats/csv/config.go
@@ -21,12 +21,11 @@
 package csv
 
 import (
+	"fmt"
 	"strings"
 	"time"
 
-	"github.com/kubernetes/helm/pkg/strvals"
 	"github.com/loadimpact/k6/lib/types"
-	"github.com/mitchellh/mapstructure"
 	"gopkg.in/guregu/null.v3"
 )
 
@@ -37,13 +36,6 @@ type Config struct {
 	SaveInterval types.NullDuration `json:"save_interval" envconfig:"K6_CSV_SAVE_INTERVAL"`
 }
 
-// config is a duplicate of ConfigFields as we can not mapstructure.Decode into
-// null types so we duplicate the struct with primitive types to Decode into
-type config struct {
-	FileName     string `json:"file_name" mapstructure:"file_name" envconfig:"K6_CSV_FILENAME"`
-	SaveInterval string `json:"save_interval" mapstructure:"save_interval" envconfig:"K6_CSV_SAVE_INTERVAL"`
-}
-
 // NewConfig creates a new Config instance with default values for some fields.
 func NewConfig() Config {
 	return Config{
@@ -73,26 +65,24 @@ func ParseArg(arg string) (Config, error) {
 		return c, nil
 	}
 
-	params, err := strvals.Parse(arg)
-
-	if err != nil {
-		return c, err
-	}
-
-	if v, ok := params["save_interval"].(string); ok {
-		err = c.SaveInterval.UnmarshalText([]byte(v))
-		if err != nil {
-			return c, err
+	pairs := strings.Split(arg, ",")
+	for _, pair := range pairs {
+		r := strings.SplitN(pair, "=", 2)
+		if len(r) != 2 {
+			return c, fmt.Errorf("couldn't parse %q as argument for csv output", arg)
+		}
+		switch r[0] {
+		case "save_interval":
+			err := c.SaveInterval.UnmarshalText([]byte(r[1]))
+			if err != nil {
+				return c, err
+			}
+		case "file_name":
+			c.FileName = null.StringFrom(r[1])
+		default:
+			return c, fmt.Errorf("unknown key %q as argument for csv output", r[0])
 		}
 	}
 
-	var cfg config
-	err = mapstructure.Decode(params, &cfg)
-	if err != nil {
-		return c, err
-	}
-
-	c.FileName = null.StringFrom(cfg.FileName)
-
 	return c, nil
 }
diff --git a/stats/csv/config_test.go b/stats/csv/config_test.go
index 1ed37a54f72..31eafa1fe4b 100644
--- a/stats/csv/config_test.go
+++ b/stats/csv/config_test.go
@@ -75,32 +75,46 @@ func TestApply(t *testing.T) {
 }
 
 func TestParseArg(t *testing.T) {
-	args := []string{
-		"test_file.csv",
-		"file_name=test.csv,save_interval=5s",
-	}
-
-	expected := []Config{
-		{
-			FileName:     null.StringFrom("test_file.csv"),
-			SaveInterval: types.NullDurationFrom(1 * time.Second),
+	cases := map[string]struct {
+		config      Config
+		expectedErr bool
+	}{
+		"test_file.csv": {
+			config: Config{
+				FileName:     null.StringFrom("test_file.csv"),
+				SaveInterval: types.NullDurationFrom(1 * time.Second),
+			},
 		},
-		{
-			FileName:     null.StringFrom("test.csv"),
-			SaveInterval: types.NullDurationFrom(5 * time.Second),
+		"save_interval=5s": {
+			config: Config{
+				SaveInterval: types.NullDurationFrom(5 * time.Second),
+			},
+		},
+		"file_name=test.csv,save_interval=5s": {
+			config: Config{
+				FileName:     null.StringFrom("test.csv"),
+				SaveInterval: types.NullDurationFrom(5 * time.Second),
+			},
+		},
+		"filename=test.csv,save_interval=5s": {
+			expectedErr: true,
 		},
 	}
 
-	for i := range args {
-		arg := args[i]
-		expected := expected[i]
+	for arg, testCase := range cases {
+		arg := arg
+		testCase := testCase
 
-		t.Run(expected.FileName.String+"_"+expected.SaveInterval.String(), func(t *testing.T) {
+		t.Run(arg, func(t *testing.T) {
 			config, err := ParseArg(arg)
 
-			assert.Nil(t, err)
-			assert.Equal(t, expected.FileName.String, config.FileName.String)
-			assert.Equal(t, expected.SaveInterval.String(), config.SaveInterval.String())
+			if testCase.expectedErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, testCase.config.FileName.String, config.FileName.String)
+			assert.Equal(t, testCase.config.SaveInterval.String(), config.SaveInterval.String())
 		})
 	}
 }