diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 7868e299cfcad..8d3b780b1b302 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -856,9 +856,8 @@ macro_rules! int_impl {
         ///
         /// # Return value
         ///
-        /// `None` if the string did not represent a valid number.
-        /// Otherwise, `Some(n)` where `n` is the integer represented
-        /// by `src`.
+        /// `Err(ParseIntError)` if the string did not represent a valid number.
+        /// Otherwise, `Ok(n)` where `n` is the integer represented by `src`.
         #[stable(feature = "rust1", since = "1.0.0")]
         #[allow(deprecated)]
         pub fn from_str_radix(src: &str, radix: u32) -> Result<$T, ParseIntError> {
@@ -1374,9 +1373,8 @@ macro_rules! uint_impl {
         ///
         /// # Return value
         ///
-        /// `None` if the string did not represent a valid number.
-        /// Otherwise, `Some(n)` where `n` is the integer represented
-        /// by `src`.
+        /// `Err(ParseIntError)` if the string did not represent a valid number.
+        /// Otherwise, `Ok(n)` where `n` is the integer represented by `src`.
         #[stable(feature = "rust1", since = "1.0.0")]
         #[allow(deprecated)]
         pub fn from_str_radix(src: &str, radix: u32) -> Result<$T, ParseIntError> {
@@ -2707,8 +2705,8 @@ macro_rules! from_str_radix_float_impl {
             ///
             /// # Return value
             ///
-            /// `None` if the string did not represent a valid number.  Otherwise,
-            /// `Some(n)` where `n` is the floating-point number represented by `src`.
+            /// `Err(ParseIntError)` if the string did not represent a valid number.  Otherwise,
+            /// Otherwise, `Ok(n)` where `n` is the floating-point number represented by `src`.
             #[inline]
             #[allow(deprecated)]
             fn from_str(src: &str) -> Result<$T, ParseFloatError> {
@@ -2736,9 +2734,8 @@ macro_rules! from_str_radix_float_impl {
             ///
             /// # Return value
             ///
-            /// `None` if the string did not represent a valid number.
-            /// Otherwise, `Some(n)` where `n` is the floating-point number
-            /// represented by `src`.
+            /// `Err(ParseIntError)` if the string did not represent a valid number.  Otherwise,
+            /// Otherwise, `Ok(n)` where `n` is the floating-point number represented by `src`.
             fn from_str_radix(src: &str, radix: u32)
                               -> Result<$T, ParseFloatError> {
                 use self::FloatErrorKind::*;