diff --git a/openstack/db/v1/instances/requests.go b/openstack/db/v1/instances/requests.go
index d87fdec..63406c7 100644
--- a/openstack/db/v1/instances/requests.go
+++ b/openstack/db/v1/instances/requests.go
@@ -174,12 +174,16 @@
 func ResizeInstance(client *gophercloud.ServiceClient, id, flavorRef string) ActionResult {
 	var res ActionResult
 
-	reqBody := map[string]map[string]string{
-		"resize": map[string]string{
-			"flavorRef": flavorRef,
-		},
+	type resize struct {
+		FlavorRef string `json:"flavorRef"`
 	}
 
+	type req struct {
+		Resize resize `json:"resize"`
+	}
+
+	reqBody := req{Resize: resize{FlavorRef: flavorRef}}
+
 	_, res.Err = client.Request("POST", actionURL(client, id), gophercloud.RequestOpts{
 		JSONBody: reqBody,
 		OkCodes:  []int{202},
@@ -194,12 +198,20 @@
 func ResizeVolume(client *gophercloud.ServiceClient, id string, size int) ActionResult {
 	var res ActionResult
 
-	reqBody := map[string]map[string]map[string]int{
-		"resize": map[string]map[string]int{
-			"volume": map[string]int{"size": size},
-		},
+	type volume struct {
+		Size int `json:"size"`
 	}
 
+	type resize struct {
+		Volume volume `json:"volume"`
+	}
+
+	type req struct {
+		Resize resize `json:"resize"`
+	}
+
+	reqBody := req{Resize: resize{Volume: volume{Size: size}}}
+
 	_, res.Err = client.Request("POST", actionURL(client, id), gophercloud.RequestOpts{
 		JSONBody: reqBody,
 		OkCodes:  []int{202},