diff --git a/generate/testdata/queries/InterfaceNesting.graphql b/generate/testdata/queries/InterfaceNesting.graphql
new file mode 100644
index 0000000..be0151d
--- /dev/null
+++ b/generate/testdata/queries/InterfaceNesting.graphql
@@ -0,0 +1,14 @@
+query InterfaceNesting {
+  root {
+    id
+    children {
+      id
+      parent {
+        id
+        children {
+          id
+        }
+      }
+    }
+  }
+}
diff --git a/generate/testdata/queries/InterfaceNesting.graphql.go b/generate/testdata/queries/InterfaceNesting.graphql.go
new file mode 100644
index 0000000..a9047bd
--- /dev/null
+++ b/generate/testdata/queries/InterfaceNesting.graphql.go
@@ -0,0 +1,354 @@
+package test
+
+// Code generated by github.com/Khan/genqlient, DO NOT EDIT.
+
+import (
+	"encoding/json"
+
+	"github.com/Khan/genqlient/graphql"
+	"github.com/me/mypkg"
+)
+
+type InterfaceNestingResponse struct {
+	Root InterfaceNestingRootTopic `json:"root"`
+}
+
+type InterfaceNestingRootTopic struct {
+	Id       mypkg.ID                                   `json:"id"`
+	Children []InterfaceNestingRootTopicChildrenContent `json:"-"`
+}
+
+func (v *InterfaceNestingRootTopic) UnmarshalJSON(b []byte) error {
+	var firstPass struct {
+		*InterfaceNestingRootTopic
+		Children json.RawMessage `json:"children"`
+	}
+	firstPass.InterfaceNestingRootTopic = v
+
+	err := json.Unmarshal(b, &firstPass)
+	if err != nil {
+		return err
+	}
+
+	var tn struct {
+		TypeName string `json:"__typename"`
+	}
+	err = json.Unmarshal(firstPass.Children, &tn)
+	if err != nil {
+		return err
+	}
+	switch tn.TypeName {
+
+	case "Article":
+
+		v.Children = InterfaceNestingRootTopicChildrenArticle{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Video":
+
+		v.Children = InterfaceNestingRootTopicChildrenVideo{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Topic":
+
+		v.Children = InterfaceNestingRootTopicChildrenTopic{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	}
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+type InterfaceNestingRootTopicChildrenArticle struct {
+	Id     mypkg.ID                                            `json:"id"`
+	Parent InterfaceNestingRootTopicChildrenArticleParentTopic `json:"parent"`
+}
+
+func (v InterfaceNestingRootTopicChildrenArticle) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenArticleParentTopic struct {
+	Id       mypkg.ID                                                             `json:"id"`
+	Children []InterfaceNestingRootTopicChildrenArticleParentTopicChildrenContent `json:"-"`
+}
+
+func (v *InterfaceNestingRootTopicChildrenArticleParentTopic) UnmarshalJSON(b []byte) error {
+	var firstPass struct {
+		*InterfaceNestingRootTopicChildrenArticleParentTopic
+		Children json.RawMessage `json:"children"`
+	}
+	firstPass.InterfaceNestingRootTopicChildrenArticleParentTopic = v
+
+	err := json.Unmarshal(b, &firstPass)
+	if err != nil {
+		return err
+	}
+
+	var tn struct {
+		TypeName string `json:"__typename"`
+	}
+	err = json.Unmarshal(firstPass.Children, &tn)
+	if err != nil {
+		return err
+	}
+	switch tn.TypeName {
+
+	case "Article":
+
+		v.Children = InterfaceNestingRootTopicChildrenArticleParentTopicChildrenArticle{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Video":
+
+		v.Children = InterfaceNestingRootTopicChildrenArticleParentTopicChildrenVideo{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Topic":
+
+		v.Children = InterfaceNestingRootTopicChildrenArticleParentTopicChildrenTopic{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	}
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+type InterfaceNestingRootTopicChildrenArticleParentTopicChildrenArticle struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenArticleParentTopicChildrenArticle) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenArticleParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenArticleParentTopicChildrenContent interface {
+	implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenArticleParentTopicChildrenContent()
+}
+
+type InterfaceNestingRootTopicChildrenArticleParentTopicChildrenTopic struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenArticleParentTopicChildrenTopic) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenArticleParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenArticleParentTopicChildrenVideo struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenArticleParentTopicChildrenVideo) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenArticleParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenContent interface {
+	implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenContent()
+}
+
+type InterfaceNestingRootTopicChildrenTopic struct {
+	Id     mypkg.ID                                          `json:"id"`
+	Parent InterfaceNestingRootTopicChildrenTopicParentTopic `json:"parent"`
+}
+
+func (v InterfaceNestingRootTopicChildrenTopic) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenTopicParentTopic struct {
+	Id       mypkg.ID                                                           `json:"id"`
+	Children []InterfaceNestingRootTopicChildrenTopicParentTopicChildrenContent `json:"-"`
+}
+
+func (v *InterfaceNestingRootTopicChildrenTopicParentTopic) UnmarshalJSON(b []byte) error {
+	var firstPass struct {
+		*InterfaceNestingRootTopicChildrenTopicParentTopic
+		Children json.RawMessage `json:"children"`
+	}
+	firstPass.InterfaceNestingRootTopicChildrenTopicParentTopic = v
+
+	err := json.Unmarshal(b, &firstPass)
+	if err != nil {
+		return err
+	}
+
+	var tn struct {
+		TypeName string `json:"__typename"`
+	}
+	err = json.Unmarshal(firstPass.Children, &tn)
+	if err != nil {
+		return err
+	}
+	switch tn.TypeName {
+
+	case "Article":
+
+		v.Children = InterfaceNestingRootTopicChildrenTopicParentTopicChildrenArticle{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Video":
+
+		v.Children = InterfaceNestingRootTopicChildrenTopicParentTopicChildrenVideo{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Topic":
+
+		v.Children = InterfaceNestingRootTopicChildrenTopicParentTopicChildrenTopic{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	}
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+type InterfaceNestingRootTopicChildrenTopicParentTopicChildrenArticle struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenTopicParentTopicChildrenArticle) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenTopicParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenTopicParentTopicChildrenContent interface {
+	implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenTopicParentTopicChildrenContent()
+}
+
+type InterfaceNestingRootTopicChildrenTopicParentTopicChildrenTopic struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenTopicParentTopicChildrenTopic) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenTopicParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenTopicParentTopicChildrenVideo struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenTopicParentTopicChildrenVideo) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenTopicParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenVideo struct {
+	Id     mypkg.ID                                          `json:"id"`
+	Parent InterfaceNestingRootTopicChildrenVideoParentTopic `json:"parent"`
+}
+
+func (v InterfaceNestingRootTopicChildrenVideo) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenVideoParentTopic struct {
+	Id       mypkg.ID                                                           `json:"id"`
+	Children []InterfaceNestingRootTopicChildrenVideoParentTopicChildrenContent `json:"-"`
+}
+
+func (v *InterfaceNestingRootTopicChildrenVideoParentTopic) UnmarshalJSON(b []byte) error {
+	var firstPass struct {
+		*InterfaceNestingRootTopicChildrenVideoParentTopic
+		Children json.RawMessage `json:"children"`
+	}
+	firstPass.InterfaceNestingRootTopicChildrenVideoParentTopic = v
+
+	err := json.Unmarshal(b, &firstPass)
+	if err != nil {
+		return err
+	}
+
+	var tn struct {
+		TypeName string `json:"__typename"`
+	}
+	err = json.Unmarshal(firstPass.Children, &tn)
+	if err != nil {
+		return err
+	}
+	switch tn.TypeName {
+
+	case "Article":
+
+		v.Children = InterfaceNestingRootTopicChildrenVideoParentTopicChildrenArticle{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Video":
+
+		v.Children = InterfaceNestingRootTopicChildrenVideoParentTopicChildrenVideo{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	case "Topic":
+
+		v.Children = InterfaceNestingRootTopicChildrenVideoParentTopicChildrenTopic{}
+		err = json.Unmarshal(
+			firstPass.Children, &v.Children)
+
+	}
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+type InterfaceNestingRootTopicChildrenVideoParentTopicChildrenArticle struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenVideoParentTopicChildrenArticle) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenVideoParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenVideoParentTopicChildrenContent interface {
+	implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenVideoParentTopicChildrenContent()
+}
+
+type InterfaceNestingRootTopicChildrenVideoParentTopicChildrenTopic struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenVideoParentTopicChildrenTopic) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenVideoParentTopicChildrenContent() {
+}
+
+type InterfaceNestingRootTopicChildrenVideoParentTopicChildrenVideo struct {
+	Id mypkg.ID `json:"id"`
+}
+
+func (v InterfaceNestingRootTopicChildrenVideoParentTopicChildrenVideo) implementsGraphQLInterfaceInterfaceNestingRootTopicChildrenVideoParentTopicChildrenContent() {
+}
+
+func InterfaceNesting(
+	client graphql.Client,
+) (*InterfaceNestingResponse, error) {
+	var retval InterfaceNestingResponse
+	err := client.MakeRequest(
+		nil,
+		"InterfaceNesting",
+		`
+query InterfaceNesting {
+	root {
+		id
+		children {
+			id
+			parent {
+				id
+				children {
+					id
+				}
+			}
+		}
+	}
+}
+`,
+		&retval,
+		nil,
+	)
+	return &retval, err
+}
diff --git a/generate/testdata/queries/InterfaceNesting.graphql.json b/generate/testdata/queries/InterfaceNesting.graphql.json
new file mode 100644
index 0000000..c2e973c
--- /dev/null
+++ b/generate/testdata/queries/InterfaceNesting.graphql.json
@@ -0,0 +1,9 @@
+{
+  "operations": [
+    {
+      "operationName": "InterfaceNesting",
+      "query": "\nquery InterfaceNesting {\n\troot {\n\t\tid\n\t\tchildren {\n\t\t\tid\n\t\t\tparent {\n\t\t\t\tid\n\t\t\t\tchildren {\n\t\t\t\t\tid\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n}\n",
+      "sourceLocation": "testdata/queries/InterfaceNesting.graphql"
+    }
+  ]
+}
\ No newline at end of file