diff --git a/README.md b/README.md
index f61d1b9..c379f29 100644
--- a/README.md
+++ b/README.md
@@ -51,12 +51,12 @@ n := structure.Name(s)
 // => true
 h := structure.Has(s, "Enabled")
 
-// Check if a field of a struct is initialized or not.
+// Check if any field of a struct is initialized or not.
 if structure.HasZero(s) {
     fmt.Println("s has a zero value field")
 }
 
-// Check if all field of a struct is initialized or not.
+// Check if all fields of a struct is initialized or not.
 if structure.IsZero(s) {
     fmt.Println("all fields of s is zero value")
 }
diff --git a/structure.go b/structure.go
index 5bf0955..9eadd17 100644
--- a/structure.go
+++ b/structure.go
@@ -3,6 +3,10 @@ package structure
 
 import "reflect"
 
+var (
+	DefaultTagName = "structure" // struct's field default tag name
+)
+
 // Map converts the given s struct to a map[string]interface{}, where the keys
 // of the map are the field names and the values of the map the associated
 // values of the fields. The default key string is the struct field name but
@@ -40,7 +44,7 @@ func Map(s interface{}) map[string]interface{} {
 
 		// override if the user passed a structure tag value
 		// ignore if the user passed the "-" value
-		if tag := field.Tag.Get("structure"); tag != "" {
+		if tag := field.Tag.Get(DefaultTagName); tag != "" {
 			name = tag
 		}
 
@@ -249,7 +253,7 @@ func strctInfo(s interface{}) (reflect.Value, []reflect.StructField) {
 		}
 
 		// don't check if it's omitted
-		if tag := field.Tag.Get("structure"); tag == "-" {
+		if tag := field.Tag.Get(DefaultTagName); tag == "-" {
 			continue
 		}
 
diff --git a/structure_test.go b/structure_test.go
index 28d56f4..3707216 100644
--- a/structure_test.go
+++ b/structure_test.go
@@ -110,6 +110,41 @@ func TestMap_Tag(t *testing.T) {
 
 }
 
+func TestMap_CustomTag(t *testing.T) {
+	var T = struct {
+		A string `dd:"x"`
+		B int    `dd:"y"`
+		C bool   `dd:"z"`
+	}{
+		A: "a-value",
+		B: 2,
+		C: true,
+	}
+
+	defaultName := DefaultTagName
+	DefaultTagName = "dd"
+	defer func() {
+		DefaultTagName = defaultName
+	}()
+	a := Map(T)
+
+	inMap := func(key interface{}) bool {
+		for k := range a {
+			if reflect.DeepEqual(k, key) {
+				return true
+			}
+		}
+		return false
+	}
+
+	for _, key := range []string{"x", "y", "z"} {
+		if !inMap(key) {
+			t.Errorf("Map should have the key %v", key)
+		}
+	}
+
+}
+
 func TestMap_Nested(t *testing.T) {
 	type A struct {
 		Name string