diff --git a/src/foundation.rs b/src/foundation.rs
index babc187..1840f26 100644
--- a/src/foundation.rs
+++ b/src/foundation.rs
@@ -9,7 +9,6 @@
 
 use base::{id, class};
 use libc;
-use std::ffi::CString;
 
 #[cfg(target_pointer_width = "32")]
 pub type NSInteger = libc::c_int;
@@ -21,6 +20,8 @@ pub type NSInteger = libc::c_long;
 #[cfg(target_pointer_width = "64")]
 pub type NSUInteger = libc::c_ulong;
 
+const UTF8_ENCODING: usize = 4;
+
 #[repr(C)]
 pub struct NSPoint {
     pub x: f64,
@@ -123,24 +124,26 @@ pub trait NSString {
         msg_send![class("NSString"), alloc]
     }
 
-    unsafe fn initWithUTF8String_(self, c_string: *const i8) -> id;
     unsafe fn stringByAppendingString_(self, other: id) -> id;
     unsafe fn init_str(self, string: &str) -> Self;
     unsafe fn UTF8String(self) -> *const libc::c_char;
+    unsafe fn len(self) -> usize;
 }
 
 impl NSString for id {
-    unsafe fn initWithUTF8String_(self, c_string: *const i8) -> id {
-        msg_send![self, initWithUTF8String:c_string as id]
-    }
-
     unsafe fn stringByAppendingString_(self, other: id) -> id {
         msg_send![self, stringByAppendingString:other]
     }
 
     unsafe fn init_str(self, string: &str) -> id {
-        let cstring = CString::new(string).unwrap();
-        self.initWithUTF8String_(cstring.as_ptr())
+        return msg_send![self,
+                         initWithBytes:string.as_ptr()
+                             length:string.len()
+                             encoding:UTF8_ENCODING as id];
+    }
+
+    unsafe fn len(self) -> usize {
+        msg_send![self, lengthOfBytesUsingEncoding:UTF8_ENCODING]
     }
 
     unsafe fn UTF8String(self) -> *const libc::c_char {
diff --git a/tests/foundation.rs b/tests/foundation.rs
new file mode 100644
index 0000000..c4f9130
--- /dev/null
+++ b/tests/foundation.rs
@@ -0,0 +1,59 @@
+extern crate cocoa;
+
+#[cfg(test)]
+mod foundation {
+    mod nsstring {
+        use cocoa::foundation::{NSString};
+        use cocoa::base::{nil};
+        use std::slice;
+        use std::str;
+
+        #[test]
+        fn test_utf8() {
+            let expected = "Iñtërnâtiônàlizætiøn";
+            unsafe {
+                let built = NSString::alloc(nil).init_str(expected);
+                let bytes = built.UTF8String() as *const u8;
+                let objc_string = str::from_utf8(slice::from_raw_parts(bytes, built.len())).unwrap();
+                assert!(objc_string.len() == expected.len());
+                assert!(objc_string == expected);
+            }
+        }
+
+        #[test]
+        fn test_string() {
+            let expected = "Hello World!";
+            unsafe {
+                let built = NSString::alloc(nil).init_str(expected);
+                let bytes = built.UTF8String() as *const u8;
+                let objc_string = str::from_utf8(slice::from_raw_parts(bytes, built.len())).unwrap();
+                assert!(objc_string.len() == expected.len());
+                assert!(objc_string == expected);
+            }
+        }
+
+        #[test]
+        fn test_length() {
+            let expected = "Hello!";
+            unsafe {
+                let built = NSString::alloc(nil).init_str(expected);
+                assert!(built.len() == expected.len());
+            }
+        }
+
+        #[test]
+        fn test_append_by_appending_string() {
+            let initial_str = "Iñtërnâtiônàlizætiøn";
+            let to_append = "_more_strings";
+            let expected = concat!("Iñtërnâtiônàlizætiøn", "_more_strings");
+            unsafe {
+                let built = NSString::alloc(nil).init_str(initial_str);
+                let built_to_append = NSString::alloc(nil).init_str(to_append);
+                let append_string = built.stringByAppendingString_(built_to_append);
+                let bytes = append_string.UTF8String() as *const u8;
+                let objc_string = str::from_utf8(slice::from_raw_parts(bytes, append_string.len())).unwrap();
+                assert!(objc_string == expected);
+            }
+        }
+    }
+}