diff --git a/go.mod b/go.mod
index 8092a012..7099c467 100644
--- a/go.mod
+++ b/go.mod
@@ -8,6 +8,7 @@ require (
 	github.com/Masterminds/sprig/v3 v3.1.0
 	github.com/aryann/difflib v0.0.0-20170710044230-e206f873d14a
 	github.com/frankban/quicktest v1.11.2 // indirect
+	github.com/ghodss/yaml v1.0.1-0.20190212211648-25d852aebe32
 	github.com/go-test/deep v1.0.7
 	github.com/golang/mock v1.4.4
 	github.com/google/go-cmp v0.5.2
diff --git a/go.sum b/go.sum
index 908d3d97..1ad1e4e8 100644
--- a/go.sum
+++ b/go.sum
@@ -205,6 +205,8 @@ github.com/fujiwara/tfstate-lookup v0.0.14 h1:cjSRXGRWRq57WCDt5VESFpFBNTQF18eCAv
 github.com/fujiwara/tfstate-lookup v0.0.14/go.mod h1:08o5Rm5pKzvIxoZe3D0NIT8AHYBqTzyUU03BZ/c0IKA=
 github.com/ghodss/yaml v0.0.0-20150909031657-73d445a93680/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
+github.com/ghodss/yaml v1.0.1-0.20190212211648-25d852aebe32 h1:Mn26/9ZMNWSw9C9ERFA1PUxfmGpolnw2v0bKOREu5ew=
+github.com/ghodss/yaml v1.0.1-0.20190212211648-25d852aebe32/go.mod h1:GIjDIg/heH5DOkXY3YJ/wNhfHsQHoXGjl8G8amsYQ1I=
 github.com/go-asn1-ber/asn1-ber v1.3.1/go.mod h1:hEBeB/ic+5LoWskz+yKT7vGhhPYkProFKoKdwZRWMe0=
 github.com/go-gl/glfw v0.0.0-20190409004039-e6da0acd62b1/go.mod h1:vR7hzQXu2zJy9AVAgeJqvqgH9Q5CA+iKCZ2gyEVpxRU=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20191125211704-12ad95a8df72/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
diff --git a/pkg/tmpl/context_funcs.go b/pkg/tmpl/context_funcs.go
index 5d65e585..7e64aa5d 100644
--- a/pkg/tmpl/context_funcs.go
+++ b/pkg/tmpl/context_funcs.go
@@ -2,9 +2,9 @@ package tmpl
 
 import (
 	"fmt"
+	"github.com/ghodss/yaml"
 	"github.com/roboll/helmfile/pkg/helmexec"
 	"golang.org/x/sync/errgroup"
-	"gopkg.in/yaml.v2"
 	"io"
 	"os"
 	"os/exec"
diff --git a/pkg/tmpl/context_funcs_test.go b/pkg/tmpl/context_funcs_test.go
index 3483ae89..cfc0a21d 100644
--- a/pkg/tmpl/context_funcs_test.go
+++ b/pkg/tmpl/context_funcs_test.go
@@ -1,7 +1,9 @@
 package tmpl
 
 import (
+	"encoding/json"
 	"fmt"
+	"github.com/google/go-cmp/cmp"
 	"path/filepath"
 	"reflect"
 	"testing"
@@ -47,12 +49,31 @@ func TestReadFile_PassAbsPath(t *testing.T) {
 	}
 }
 
+func TestToYaml_UnsupportedNestedMapKey(t *testing.T) {
+	expected := ``
+	vals := Values(map[string]interface{}{
+		"foo": map[interface{}]interface{}{
+			"bar": "BAR",
+		},
+	})
+	actual, err := ToYaml(vals)
+	if err == nil {
+		t.Fatalf("expected error but got none")
+	} else if err.Error() != "error marshaling into JSON: json: unsupported type: map[interface {}]interface {}" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("unexpected result: expected=%v, actual=%v", expected, actual)
+	}
+}
+
 func TestToYaml(t *testing.T) {
 	expected := `foo:
   bar: BAR
 `
 	vals := Values(map[string]interface{}{
-		"foo": map[interface{}]interface{}{
+		"foo": map[string]interface{}{
 			"bar": "BAR",
 		},
 	})
@@ -70,7 +91,7 @@ func TestFromYaml(t *testing.T) {
   bar: BAR
 `
 	expected := Values(map[string]interface{}{
-		"foo": map[interface{}]interface{}{
+		"foo": map[string]interface{}{
 			"bar": "BAR",
 		},
 	})
@@ -83,6 +104,27 @@ func TestFromYaml(t *testing.T) {
 	}
 }
 
+func TestFromYamlToJson(t *testing.T) {
+	input := `foo:
+  bar: BAR
+`
+	want := `{"foo":{"bar":"BAR"}}`
+
+	m, err := FromYaml(input)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := json.Marshal(m)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	if d := cmp.Diff(want, string(got)); d != "" {
+		t.Errorf("unexpected result: want (-), got (+):\n%s", d)
+	}
+}
+
 func TestSetValueAtPath_OneComponent(t *testing.T) {
 	input := map[string]interface{}{
 		"foo": "",