diff --git a/cmd/portal/init.go b/cmd/portal/init.go
index 16e45ab..ba8d243 100644
--- a/cmd/portal/init.go
+++ b/cmd/portal/init.go
@@ -17,36 +17,6 @@ import (
 	"go.uber.org/zap"
 )
 
-func initCheckRequiredConfig(logger *zap.Logger, config *config.Manager) error {
-	required := []string{
-		"core.domain",
-		"core.port",
-		"core.sia.url",
-		"core.sia.key",
-		"core.db.username",
-		"core.db.password",
-		"core.db.host",
-		"core.db.name",
-		"core.storage.s3.buffer_bucket",
-		"core.storage.s3.endpoint",
-		"core.storage.s3.region",
-		"core.storage.s3.access_key",
-		"core.storage.s3.secret_key",
-		"core.mail.host",
-		"core.mail.username",
-		"core.mail.password",
-		"core.portal_name",
-	}
-
-	for _, key := range required {
-		if !config.Viper().IsSet(key) {
-			logger.Fatal(key + " is required")
-		}
-	}
-
-	return nil
-}
-
 func NewIdentity(config *config.Manager, logger *zap.Logger) (ed25519.PrivateKey, error) {
 	var seed [32]byte
 	identitySeed := config.Config().Core.Identity
diff --git a/cmd/portal/main.go b/cmd/portal/main.go
index a5e9dfb..1e8a2c2 100644
--- a/cmd/portal/main.go
+++ b/cmd/portal/main.go
@@ -54,7 +54,6 @@ func main() {
 		fx.Supply(cfg),
 		fx.Supply(logger, logLevel),
 		fxLogger,
-		fx.Invoke(initCheckRequiredConfig),
 		fx.Provide(NewIdentity),
 		db.Module,
 		renter.Module,
diff --git a/config/core.go b/config/core.go
index 4b1507a..f405f65 100644
--- a/config/core.go
+++ b/config/core.go
@@ -1,8 +1,13 @@
 package config
 
-import "github.com/docker/go-units"
+import (
+	"errors"
+
+	"github.com/docker/go-units"
+)
 
 var _ Defaults = (*CoreConfig)(nil)
+var _ Validator = (*CoreConfig)(nil)
 
 type CoreConfig struct {
 	DB              DatabaseConfig `mapstructure:"db"`
@@ -20,6 +25,20 @@ type CoreConfig struct {
 	Clustered       *ClusterConfig `mapstructure:"clustered"`
 }
 
+func (c CoreConfig) Validate() error {
+	if c.Domain == "" {
+		return errors.New("core.domain is required")
+	}
+	if c.PortalName == "" {
+		return errors.New("core.portal_name is required")
+	}
+	if c.Port == 0 {
+		return errors.New("core.port is required")
+	}
+
+	return nil
+}
+
 func (c CoreConfig) Defaults() map[string]interface{} {
 	return map[string]interface{}{
 		"post_upload_limit": units.MiB * 100,
diff --git a/config/database.go b/config/database.go
index dc3e106..8eca673 100644
--- a/config/database.go
+++ b/config/database.go
@@ -1,12 +1,14 @@
 package config
 
 import (
+	"errors"
 	"reflect"
 
 	"github.com/mitchellh/mapstructure"
 )
 
 var _ Defaults = (*DatabaseConfig)(nil)
+var _ Validator = (*DatabaseConfig)(nil)
 
 type DatabaseConfig struct {
 	Charset  string       `mapstructure:"charset"`
@@ -18,8 +20,29 @@ type DatabaseConfig struct {
 	Cache    *CacheConfig `mapstructure:"cache"`
 }
 
+func (d DatabaseConfig) Validate() error {
+	if d.Host == "" {
+		return errors.New("core.db.host is required")
+	}
+	if d.Port == 0 {
+		return errors.New("core.db.port is required")
+	}
+	if d.Username == "" {
+		return errors.New("core.db.username is required")
+	}
+	if d.Password == "" {
+		return errors.New("core.db.password is required")
+	}
+	if d.Name == "" {
+		return errors.New("core.db.name is required")
+	}
+
+	return nil
+}
+
 func (d DatabaseConfig) Defaults() map[string]interface{} {
 	return map[string]interface{}{
+		"host":    "localhost",
 		"charset": "utf8mb4",
 		"port":    3306,
 		"name":    "portal",
diff --git a/config/s3.go b/config/s3.go
index 8b5f312..3899fa8 100644
--- a/config/s3.go
+++ b/config/s3.go
@@ -1,5 +1,9 @@
 package config
 
+import "errors"
+
+var _ Validator = (*DatabaseConfig)(nil)
+
 type S3Config struct {
 	BufferBucket string `mapstructure:"buffer_bucket"`
 	Endpoint     string `mapstructure:"endpoint"`
@@ -7,3 +11,22 @@ type S3Config struct {
 	AccessKey    string `mapstructure:"access_key"`
 	SecretKey    string `mapstructure:"secret_key"`
 }
+
+func (s S3Config) Validate() error {
+	if s.BufferBucket == "" {
+		return errors.New("core.storage.s3.buffer_bucket is required")
+	}
+	if s.Endpoint == "" {
+		return errors.New("core.storage.s3.endpoint is required")
+	}
+	if s.Region == "" {
+		return errors.New("core.storage.s3.region is required")
+	}
+	if s.AccessKey == "" {
+		return errors.New("core.storage.s3.access_key is required")
+	}
+	if s.SecretKey == "" {
+		return errors.New("core.storage.s3.secret_key is required")
+	}
+	return nil
+}
diff --git a/config/sia.go b/config/sia.go
index 696978f..2d194db 100644
--- a/config/sia.go
+++ b/config/sia.go
@@ -1,6 +1,20 @@
 package config
 
+import "errors"
+
+var _ Validator = (*SiaConfig)(nil)
+
 type SiaConfig struct {
 	Key string `mapstructure:"key"`
 	URL string `mapstructure:"url"`
 }
+
+func (s SiaConfig) Validate() error {
+	if s.Key == "" {
+		return errors.New("core.storage.sia.key is required")
+	}
+	if s.URL == "" {
+		return errors.New("core.storage.sia.url is required")
+	}
+	return nil
+}