diff --git a/napi/src/js_values/string/utf16.rs b/napi/src/js_values/string/utf16.rs
index 4ae5b71f..a61d997a 100644
--- a/napi/src/js_values/string/utf16.rs
+++ b/napi/src/js_values/string/utf16.rs
@@ -1,6 +1,6 @@
-use std::convert::TryFrom;
 use std::mem;
 use std::ops::Deref;
+use std::{convert::TryFrom, mem::ManuallyDrop};
 
 use crate::{Error, JsString, Result, Status};
 
@@ -33,6 +33,7 @@ impl JsStringUtf16 {
 
   #[inline]
   pub fn into_value(self) -> JsString {
+    ManuallyDrop::into_inner(self.buf);
     self.inner
   }
 }
@@ -61,6 +62,6 @@ impl AsRef<Vec<u16>> for JsStringUtf16 {
 
 impl From<JsStringUtf16> for Vec<u16> {
   fn from(value: JsStringUtf16) -> Self {
-    value.as_slice().to_vec()
+    ManuallyDrop::into_inner(value.buf)
   }
 }
diff --git a/napi/src/js_values/string/utf8.rs b/napi/src/js_values/string/utf8.rs
index 5239b383..f5c2acd9 100644
--- a/napi/src/js_values/string/utf8.rs
+++ b/napi/src/js_values/string/utf8.rs
@@ -36,16 +36,24 @@ impl JsStringUtf8 {
 
   #[inline]
   pub fn into_owned(self) -> Result<String> {
-    Ok(self.as_str()?.to_owned())
+    let buffer = ManuallyDrop::into_inner(self.buf);
+
+    let s = unsafe { CStr::from_ptr(buffer.as_ptr()) }
+      .to_str()
+      .map_err(|e| Error::new(Status::InvalidArg, format!("{}", e)))?;
+
+    Ok(s.to_owned())
   }
 
   #[inline]
   pub fn take(self) -> Vec<u8> {
-    self.as_slice().to_vec()
+    let bytes = unsafe { CStr::from_ptr(ManuallyDrop::into_inner(self.buf).as_ptr()) }.to_bytes();
+    bytes.to_vec()
   }
 
   #[inline]
   pub fn into_value(self) -> JsString {
+    ManuallyDrop::into_inner(self.buf);
     self.inner
   }
 }
@@ -54,7 +62,7 @@ impl TryFrom<JsStringUtf8> for String {
   type Error = Error;
 
   fn try_from(value: JsStringUtf8) -> Result<String> {
-    Ok(value.as_str()?.to_owned())
+    value.into_owned()
   }
 }
 
diff --git a/rustfmt.toml b/rustfmt.toml
index b196eaa2..e8fd890c 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -1 +1,2 @@
 tab_spaces = 2
+edition = "2018"