diff --git a/internal/postgres/command/migrate.go b/internal/postgres/command/migrate.go
index 171f4344..3d600d82 100644
--- a/internal/postgres/command/migrate.go
+++ b/internal/postgres/command/migrate.go
@@ -43,7 +43,7 @@ func migrateSetupCommand(parentFlags *flag.Migrate) *naistrix.Command {
 		flags.DiskAutoResize = v
 	}
 
-	if v, err := strconv.Atoi(os.Getenv("TARGET_INSTANCE_DISKSIZE")); err == nil {
+	if v, err := strconv.Atoi(os.Getenv("TARGET_INSTANCE_DISK_SIZE")); err == nil {
 		flags.DiskSize = v
 	}
 
diff --git a/internal/postgres/migrate/config/config.go b/internal/postgres/migrate/config/config.go
index 77f9d88e..19cfbf47 100644
--- a/internal/postgres/migrate/config/config.go
+++ b/internal/postgres/migrate/config/config.go
@@ -161,7 +161,7 @@ func (c *Config) CreateConfigMap() *corev1.ConfigMap {
 	c.Target.InstanceName.Do(dataBuilder[string](data, "TARGET_INSTANCE_NAME"))
 	c.Target.Tier.Do(dataBuilder[string](data, "TARGET_INSTANCE_TIER"))
 	c.Target.DiskAutoresize.Do(dataBuilder[bool](data, "TARGET_INSTANCE_DISK_AUTORESIZE"))
-	c.Target.DiskSize.Do(dataBuilder[int](data, "TARGET_INSTANCE_DISKSIZE"))
+	c.Target.DiskSize.Do(dataBuilder[int](data, "TARGET_INSTANCE_DISK_SIZE"))
 	c.Target.Type.Do(dataBuilder[string](data, "TARGET_INSTANCE_TYPE"))
 
 	c.Source.InstanceName.Do(dataBuilder[string](data, "SOURCE_INSTANCE_NAME"))