diff --git a/StringStylizer/Operator.swift b/StringStylizer/Operator.swift
index 7e4670e..d302ddc 100644
--- a/StringStylizer/Operator.swift
+++ b/StringStylizer/Operator.swift
@@ -39,6 +39,62 @@ public func + (left: NSAttributedString, right: NSAttributedString) -> NSAttribu
     return concat
 }
 
+/**
+ combine two NSAttributedString object
+ 
+ 
+ - paramter left:NSAttributedString?
+ - paramter right:NSAttributedString
+ 
+ - returns: NSAttributedString
+ */
+public func + (left: NSAttributedString?, right: NSAttributedString) -> NSAttributedString {
+    let concat = NSMutableAttributedString()
+    if let left = left {
+        concat.append(left)
+    }
+    concat.append(right)
+    return concat
+}
+
+/**
+ combine two NSAttributedString object
+ 
+ 
+ - paramter left:NSAttributedString
+ - paramter right:NSAttributedString?
+ 
+ - returns: NSAttributedString
+ */
+public func + (left: NSAttributedString, right: NSAttributedString?) -> NSAttributedString {
+    let concat = NSMutableAttributedString()
+    concat.append(left)
+    if let right = right {
+        concat.append(right)
+    }
+    return concat
+}
+
+/**
+ combine two NSAttributedString object
+ 
+ 
+ - paramter left:NSAttributedString?
+ - paramter right:NSAttributedString?
+ 
+ - returns: NSAttributedString
+ */
+public func + (left: NSAttributedString?, right: NSAttributedString?) -> NSAttributedString {
+    let concat = NSMutableAttributedString()
+    if let left = left {
+        concat.append(left)
+    }
+    if let right = right {
+        concat.append(right)
+    }
+    return concat
+}
+
 /**
  append NSAttributedString object
 
@@ -70,3 +126,23 @@ public func + (left: NSAttributedString, right: NSTextAttachment) -> NSAttribute
 public func + (left: NSTextAttachment, right: NSAttributedString) -> NSAttributedString {
     return NSAttributedString(attachment: left) + right
 }
+
+/// combine two NSAttributedString and NSTextAttachment objects
+///
+/// - Parameters:
+///   - left: NSAttributedString
+///   - right: NSTextAttachment?
+/// - Returns: combinded NSAttributedString
+public func + (left: NSAttributedString, right: NSTextAttachment?) -> NSAttributedString {
+    return left + right.flatMap(NSAttributedString.init(attachment:))
+}
+
+/// combine two NSTextAttachment and NSAttributedString objects
+///
+/// - Parameters:
+///   - left: NSTextAttachment?
+///   - right: NSAttributedString
+/// - Returns: combinded NSAttributedString
+public func + (left: NSTextAttachment?, right: NSAttributedString) -> NSAttributedString {
+    return left.flatMap(NSAttributedString.init(attachment:)) + right
+}
diff --git a/StringStylizerTests/StringStylizerTests.swift b/StringStylizerTests/StringStylizerTests.swift
index 1f76267..399ffc2 100755
--- a/StringStylizerTests/StringStylizerTests.swift
+++ b/StringStylizerTests/StringStylizerTests.swift
@@ -309,6 +309,32 @@ class StringStylizerTests: XCTestCase {
         XCTAssert(combined.isEqual(expected), "optional StringStylized strings do not add any content to the resulting NSAttributedString")
     }
     
+    func testOptionalAttributedString() {
+        let optional: NSAttributedString? = "a".stylize().attr
+        let notOptional: NSAttributedString = "b".stylize().attr
+
+        do {
+            let actual = optional + notOptional
+            
+            let expected = NSAttributedString(string: "ab")
+            XCTAssertEqual(actual, expected)
+        }
+        
+        do {
+            let actual = notOptional + optional
+            
+            let expected = NSAttributedString(string: "ba")
+            XCTAssertEqual(actual, expected)
+        }
+
+        do {
+            let actual = optional + optional
+            
+            let expected = NSAttributedString(string: "aa")
+            XCTAssertEqual(actual, expected)
+        }
+    }
+    
     // MARK:- private
     fileprivate func rgb(_ rgb: UInt, alpha: Double) -> UIColor {
         return UIColor(