diff --git a/config/fake.go b/config/fake.go
index 6daaca2c..7e362608 100644
--- a/config/fake.go
+++ b/config/fake.go
@@ -46,12 +46,16 @@ func (c *fakeConfigContainer) DefaultString(key string, defaultval string) strin
 }
 
 func (c *fakeConfigContainer) Strings(key string) []string {
-	return strings.Split(c.getData(key), ";")
+	v := c.getData(key)
+	if v == "" {
+		return nil
+	}
+	return strings.Split(v, ";")
 }
 
 func (c *fakeConfigContainer) DefaultStrings(key string, defaultval []string) []string {
 	v := c.Strings(key)
-	if len(v) == 0 {
+	if v == nil {
 		return defaultval
 	}
 	return v
diff --git a/config/ini.go b/config/ini.go
index a690ede0..9c19b9b1 100644
--- a/config/ini.go
+++ b/config/ini.go
@@ -269,10 +269,11 @@ func (c *IniConfigContainer) DefaultString(key string, defaultval string) string
 }
 
 // Strings returns the []string value for a given key.
+// Return nil if config value does not exist or is empty.
 func (c *IniConfigContainer) Strings(key string) []string {
 	v := c.String(key)
 	if v == "" {
-		return []string{}
+		return nil
 	}
 	return strings.Split(v, ";")
 }
@@ -281,7 +282,7 @@ func (c *IniConfigContainer) Strings(key string) []string {
 // if err != nil return defaltval
 func (c *IniConfigContainer) DefaultStrings(key string, defaultval []string) []string {
 	v := c.Strings(key)
-	if len(v) == 0 {
+	if v == nil {
 		return defaultval
 	}
 	return v
diff --git a/config/json.go b/config/json.go
index 0bc1d456..fce517eb 100644
--- a/config/json.go
+++ b/config/json.go
@@ -173,7 +173,7 @@ func (c *JSONConfigContainer) DefaultString(key string, defaultval string) strin
 func (c *JSONConfigContainer) Strings(key string) []string {
 	stringVal := c.String(key)
 	if stringVal == "" {
-		return []string{}
+		return nil
 	}
 	return strings.Split(c.String(key), ";")
 }
@@ -181,7 +181,7 @@ func (c *JSONConfigContainer) Strings(key string) []string {
 // DefaultStrings returns the []string value for a given key.
 // if err != nil return defaltval
 func (c *JSONConfigContainer) DefaultStrings(key string, defaultval []string) []string {
-	if v := c.Strings(key); len(v) > 0 {
+	if v := c.Strings(key); v != nil {
 		return v
 	}
 	return defaultval
diff --git a/config/xml/xml.go b/config/xml/xml.go
index 2757b0bc..b5291bf4 100644
--- a/config/xml/xml.go
+++ b/config/xml/xml.go
@@ -176,7 +176,7 @@ func (c *ConfigContainer) DefaultString(key string, defaultval string) string {
 func (c *ConfigContainer) Strings(key string) []string {
 	v := c.String(key)
 	if v == "" {
-		return []string{}
+		return nil
 	}
 	return strings.Split(v, ";")
 }
@@ -185,7 +185,7 @@ func (c *ConfigContainer) Strings(key string) []string {
 // if err != nil return defaltval
 func (c *ConfigContainer) DefaultStrings(key string, defaultval []string) []string {
 	v := c.Strings(key)
-	if len(v) == 0 {
+	if v == nil {
 		return defaultval
 	}
 	return v
diff --git a/config/xml/xml_test.go b/config/xml/xml_test.go
index 308e257d..60dcba54 100644
--- a/config/xml/xml_test.go
+++ b/config/xml/xml_test.go
@@ -82,7 +82,7 @@ func TestXML(t *testing.T) {
 	if xmlconf.String("name") != "astaxie" {
 		t.Fatal("get name error")
 	}
-	if len(xmlconf.Strings("emptystrings")) != 0 {
+	if xmlconf.Strings("emptystrings") != nil {
 		t.Fatal("get emtpy strings error")
 	}
 }
diff --git a/config/yaml/yaml.go b/config/yaml/yaml.go
index 9a4fb2e9..7e1d0426 100644
--- a/config/yaml/yaml.go
+++ b/config/yaml/yaml.go
@@ -213,7 +213,7 @@ func (c *ConfigContainer) DefaultString(key string, defaultval string) string {
 func (c *ConfigContainer) Strings(key string) []string {
 	v := c.String(key)
 	if v == "" {
-		return []string{}
+		return nil
 	}
 	return strings.Split(v, ";")
 }
@@ -222,7 +222,7 @@ func (c *ConfigContainer) Strings(key string) []string {
 // if err != nil return defaltval
 func (c *ConfigContainer) DefaultStrings(key string, defaultval []string) []string {
 	v := c.Strings(key)
-	if len(v) == 0 {
+	if v == nil {
 		return defaultval
 	}
 	return v
diff --git a/config/yaml/yaml_test.go b/config/yaml/yaml_test.go
index 3bbaaa32..80cbb8fe 100644
--- a/config/yaml/yaml_test.go
+++ b/config/yaml/yaml_test.go
@@ -80,7 +80,7 @@ func TestYaml(t *testing.T) {
 		t.Fatal("get name error")
 	}
 
-	if len(yamlconf.Strings("emptystrings")) != 0 {
+	if yamlconf.Strings("emptystrings") != nil {
 		t.Fatal("get emtpy strings error")
 	}
 }