diff --git a/api/typeinfo/type_info.go b/api/typeinfo/type_info.go
new file mode 100644
index 00000000..c3385314
--- /dev/null
+++ b/api/typeinfo/type_info.go
@@ -0,0 +1,3 @@
+package typeinfo
+
+const Suffix = "__type"
diff --git a/controllers/tf_controller_outputs.go b/controllers/tf_controller_outputs.go
index b0c96935..cca9af55 100644
--- a/controllers/tf_controller_outputs.go
+++ b/controllers/tf_controller_outputs.go
@@ -7,8 +7,8 @@ import (
 	"strings"
 
 	eventv1 "github.com/fluxcd/pkg/apis/event/v1beta1"
-
 	"github.com/hashicorp/terraform-exec/tfexec"
+	"github.com/weaveworks/tf-controller/api/typeinfo"
 	infrav1 "github.com/weaveworks/tf-controller/api/v1alpha2"
 	"github.com/weaveworks/tf-controller/runner"
 	"github.com/zclconf/go-cty/cty"
@@ -166,7 +166,7 @@ func (r *TerraformReconciler) writeOutput(ctx context.Context, terraform infrav1
 			data[outputOrAlias] = []byte(cv.AsString())
 		} else {
 			data[outputOrAlias] = outputMeta.Value
-			data[outputOrAlias+"__type"] = outputMeta.Type
+			data[outputOrAlias+typeinfo.Suffix] = outputMeta.Type
 		}
 	}
 
diff --git a/runner/read_inputs_test.go b/runner/read_inputs_test.go
index a5439389..de4c0942 100644
--- a/runner/read_inputs_test.go
+++ b/runner/read_inputs_test.go
@@ -8,6 +8,7 @@ import (
 	"github.com/go-logr/logr"
 	"github.com/hashicorp/hcl2/hcldec"
 	"github.com/hashicorp/hcl2/hclparse"
+	"github.com/weaveworks/tf-controller/api/typeinfo"
 	infrav1 "github.com/weaveworks/tf-controller/api/v1alpha2"
 	"github.com/zclconf/go-cty/cty"
 	ctyjson "github.com/zclconf/go-cty/cty/json"
@@ -72,7 +73,7 @@ j = { a = 1, b = 2, c = 3 }
 
 		tt, err := ctyjson.MarshalType(vv.Type())
 		g.Expect(err).To(BeNil())
-		data[k+".type"] = tt
+		data[k+typeinfo.Suffix] = tt
 		raw, err := ctyjson.Marshal(vv, vv.Type())
 		g.Expect(err).To(BeNil())
 		data[k] = raw
diff --git a/runner/server_generate_tf_vars.go b/runner/server_generate_tf_vars.go
index 50844a06..50c0d90e 100644
--- a/runner/server_generate_tf_vars.go
+++ b/runner/server_generate_tf_vars.go
@@ -11,6 +11,7 @@ import (
 	"text/template"
 
 	"github.com/go-logr/logr"
+	"github.com/weaveworks/tf-controller/api/typeinfo"
 	infrav1 "github.com/weaveworks/tf-controller/api/v1alpha2"
 	"github.com/weaveworks/tf-controller/utils"
 	"github.com/zclconf/go-cty/cty"
@@ -141,7 +142,7 @@ func ctyValueToGoValue(ctyValue cty.Value) (interface{}, error) {
 func convertSecretDataToInputs(log logr.Logger, secret *v1.Secret) (map[string]interface{}, error) {
 	var keys []string
 	for k := range secret.Data {
-		if strings.HasSuffix(k, ".type") {
+		if strings.HasSuffix(k, typeinfo.Suffix) {
 			continue
 		}
 		keys = append(keys, k)
@@ -149,7 +150,7 @@ func convertSecretDataToInputs(log logr.Logger, secret *v1.Secret) (map[string]i
 
 	data := map[string]interface{}{}
 	for _, key := range keys {
-		typeInfo, exist := secret.Data[key+".type"]
+		typeInfo, exist := secret.Data[key+typeinfo.Suffix]
 		if exist {
 			raw := secret.Data[key]
 			ct, err := json.UnmarshalType(typeInfo)