diff --git a/codegen/input.gotpl b/codegen/input.gotpl
index e8a5b50492b..c6eac4d47bb 100644
--- a/codegen/input.gotpl
+++ b/codegen/input.gotpl
@@ -2,7 +2,10 @@
 	{{- if not .HasUnmarshal }}
 	func (ec *executionContext) unmarshalInput{{ .Name }}(ctx context.Context, obj interface{}) ({{.Type | ref}}, error) {
 		var it {{.Type | ref}}
-		var asMap = obj.(map[string]interface{})
+		asMap := map[string]interface{}{}
+		for k, v := range obj.(map[string]interface{}) {
+			asMap[k] = v
+		}
 		{{ range $field := .Fields}}
 			{{- if $field.Default}}
 				if _, present := asMap[{{$field.Name|quote}}] ; !present {
diff --git a/codegen/testserver/generated.go b/codegen/testserver/generated.go
index 497b5e7b65c..e2d59510a01 100644
--- a/codegen/testserver/generated.go
+++ b/codegen/testserver/generated.go
@@ -9873,7 +9873,10 @@ func (ec *executionContext) _iIt_id(ctx context.Context, field graphql.Collected
 
 func (ec *executionContext) unmarshalInputInnerDirectives(ctx context.Context, obj interface{}) (InnerDirectives, error) {
 	var it InnerDirectives
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -9915,7 +9918,10 @@ func (ec *executionContext) unmarshalInputInnerDirectives(ctx context.Context, o
 
 func (ec *executionContext) unmarshalInputInnerInput(ctx context.Context, obj interface{}) (InnerInput, error) {
 	var it InnerInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -9935,7 +9941,10 @@ func (ec *executionContext) unmarshalInputInnerInput(ctx context.Context, obj in
 
 func (ec *executionContext) unmarshalInputInputDirectives(ctx context.Context, obj interface{}) (InputDirectives, error) {
 	var it InputDirectives
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -10055,7 +10064,10 @@ func (ec *executionContext) unmarshalInputInputDirectives(ctx context.Context, o
 
 func (ec *executionContext) unmarshalInputInputWithEnumValue(ctx context.Context, obj interface{}) (InputWithEnumValue, error) {
 	var it InputWithEnumValue
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -10075,7 +10087,10 @@ func (ec *executionContext) unmarshalInputInputWithEnumValue(ctx context.Context
 
 func (ec *executionContext) unmarshalInputNestedInput(ctx context.Context, obj interface{}) (NestedInput, error) {
 	var it NestedInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -10095,7 +10110,10 @@ func (ec *executionContext) unmarshalInputNestedInput(ctx context.Context, obj i
 
 func (ec *executionContext) unmarshalInputNestedMapInput(ctx context.Context, obj interface{}) (NestedMapInput, error) {
 	var it NestedMapInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -10115,7 +10133,10 @@ func (ec *executionContext) unmarshalInputNestedMapInput(ctx context.Context, ob
 
 func (ec *executionContext) unmarshalInputOuterInput(ctx context.Context, obj interface{}) (OuterInput, error) {
 	var it OuterInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -10135,7 +10156,10 @@ func (ec *executionContext) unmarshalInputOuterInput(ctx context.Context, obj in
 
 func (ec *executionContext) unmarshalInputRecursiveInputSlice(ctx context.Context, obj interface{}) (RecursiveInputSlice, error) {
 	var it RecursiveInputSlice
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -10155,7 +10179,10 @@ func (ec *executionContext) unmarshalInputRecursiveInputSlice(ctx context.Contex
 
 func (ec *executionContext) unmarshalInputSpecialInput(ctx context.Context, obj interface{}) (SpecialInput, error) {
 	var it SpecialInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
@@ -10175,7 +10202,10 @@ func (ec *executionContext) unmarshalInputSpecialInput(ctx context.Context, obj
 
 func (ec *executionContext) unmarshalInputValidInput(ctx context.Context, obj interface{}) (ValidInput, error) {
 	var it ValidInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
diff --git a/example/config/generated.go b/example/config/generated.go
index b4916887c53..cfb6c70d2f9 100644
--- a/example/config/generated.go
+++ b/example/config/generated.go
@@ -1844,7 +1844,10 @@ func (ec *executionContext) ___Type_ofType(ctx context.Context, field graphql.Co
 
 func (ec *executionContext) unmarshalInputNewTodo(ctx context.Context, obj interface{}) (NewTodo, error) {
 	var it NewTodo
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
diff --git a/example/fileupload/generated.go b/example/fileupload/generated.go
index 5aa3d87c0c8..bd1176864b8 100644
--- a/example/fileupload/generated.go
+++ b/example/fileupload/generated.go
@@ -1923,7 +1923,10 @@ func (ec *executionContext) ___Type_ofType(ctx context.Context, field graphql.Co
 
 func (ec *executionContext) unmarshalInputUploadFile(ctx context.Context, obj interface{}) (model.UploadFile, error) {
 	var it model.UploadFile
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
diff --git a/example/scalars/generated.go b/example/scalars/generated.go
index fcfcba5244f..344dcb6f15b 100644
--- a/example/scalars/generated.go
+++ b/example/scalars/generated.go
@@ -2181,7 +2181,10 @@ func (ec *executionContext) ___Type_ofType(ctx context.Context, field graphql.Co
 
 func (ec *executionContext) unmarshalInputSearchArgs(ctx context.Context, obj interface{}) (model.SearchArgs, error) {
 	var it model.SearchArgs
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
diff --git a/example/starwars/generated/exec.go b/example/starwars/generated/exec.go
index 5034214bfcd..2fd0cbe2e36 100644
--- a/example/starwars/generated/exec.go
+++ b/example/starwars/generated/exec.go
@@ -3519,7 +3519,10 @@ func (ec *executionContext) ___Type_ofType(ctx context.Context, field graphql.Co
 
 func (ec *executionContext) unmarshalInputReviewInput(ctx context.Context, obj interface{}) (models.Review, error) {
 	var it models.Review
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
diff --git a/example/todo/generated.go b/example/todo/generated.go
index 8c467913b0e..48855b3a4b8 100644
--- a/example/todo/generated.go
+++ b/example/todo/generated.go
@@ -1888,7 +1888,10 @@ func (ec *executionContext) ___Type_ofType(ctx context.Context, field graphql.Co
 
 func (ec *executionContext) unmarshalInputTodoInput(ctx context.Context, obj interface{}) (TodoInput, error) {
 	var it TodoInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
diff --git a/example/type-system-extension/generated.go b/example/type-system-extension/generated.go
index 09cc17b5a86..9b27fddd680 100644
--- a/example/type-system-extension/generated.go
+++ b/example/type-system-extension/generated.go
@@ -1909,7 +1909,10 @@ func (ec *executionContext) ___Type_ofType(ctx context.Context, field graphql.Co
 
 func (ec *executionContext) unmarshalInputTodoInput(ctx context.Context, obj interface{}) (TodoInput, error) {
 	var it TodoInput
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	for k, v := range asMap {
 		switch k {
diff --git a/integration/generated.go b/integration/generated.go
index 12ea40452ad..ded2c49f00e 100644
--- a/integration/generated.go
+++ b/integration/generated.go
@@ -2048,7 +2048,10 @@ func (ec *executionContext) ___Type_ofType(ctx context.Context, field graphql.Co
 
 func (ec *executionContext) unmarshalInputDateFilter(ctx context.Context, obj interface{}) (models.DateFilter, error) {
 	var it models.DateFilter
-	var asMap = obj.(map[string]interface{})
+	asMap := map[string]interface{}{}
+	for k, v := range obj.(map[string]interface{}) {
+		asMap[k] = v
+	}
 
 	if _, present := asMap["timezone"]; !present {
 		asMap["timezone"] = "UTC"