diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index ed727aa2..ad3d39eb 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -32,7 +32,7 @@ use collections::enum_set::{CLike, EnumSet};
 #[cfg(all(feature = "nightly", feature = "collections"))]
 use collections::borrow::ToOwned;
 
-use core::hash::Hash;
+use core::hash::{Hash, BuildHasher};
 use core::marker::PhantomData;
 #[cfg(feature = "std")]
 use std::net;
@@ -726,31 +726,26 @@ tuple_impls! {
 macro_rules! map_impl {
     (
         $ty:ty,
-        < $($constraints:ident),* >,
-        $visitor_name:ident,
+        $visitor_ty:ident < $($typaram:ident : $bound1:ident $(+ $bound2:ident)*),* >,
         $visitor:ident,
         $ctor:expr,
-        $with_capacity:expr,
-        $insert:expr
+        $with_capacity:expr
     ) => {
         /// A visitor that produces a map.
-        pub struct $visitor_name<K, V> {
+        pub struct $visitor_ty<$($typaram),*> {
             marker: PhantomData<$ty>,
         }
 
-        impl<K, V> $visitor_name<K, V> {
+        impl<$($typaram : $bound1 $(+ $bound2)*),*> $visitor_ty<$($typaram),*> {
             /// Construct a `MapVisitor*<T>`.
             pub fn new() -> Self {
-                $visitor_name {
+                $visitor_ty {
                     marker: PhantomData,
                 }
             }
         }
 
-        impl<K, V> Visitor for $visitor_name<K, V>
-            where K: $($constraints +)*,
-                  V: Deserialize,
-        {
+        impl<$($typaram : $bound1 $(+ $bound2)*),*> Visitor for $visitor_ty<$($typaram),*> {
             type Value = $ty;
 
             #[inline]
@@ -767,7 +762,7 @@ macro_rules! map_impl {
                 let mut values = $with_capacity;
 
                 while let Some((key, value)) = try!($visitor.visit()) {
-                    $insert(&mut values, key, value);
+                    values.insert(key, value);
                 }
 
                 try!($visitor.end());
@@ -776,14 +771,11 @@ macro_rules! map_impl {
             }
         }
 
-        impl<K, V> Deserialize for $ty
-            where K: $($constraints +)*,
-                  V: Deserialize,
-        {
+        impl<$($typaram : $bound1 $(+ $bound2)*),*> Deserialize for $ty {
             fn deserialize<D>(deserializer: &mut D) -> Result<$ty, D::Error>
                 where D: Deserializer,
             {
-                deserializer.deserialize_map($visitor_name::new())
+                deserializer.deserialize_map($visitor_ty::new())
             }
         }
     }
@@ -792,22 +784,21 @@ macro_rules! map_impl {
 #[cfg(any(feature = "std", feature = "collections"))]
 map_impl!(
     BTreeMap<K, V>,
-    <Deserialize, Eq, Ord>,
-    BTreeMapVisitor,
+    BTreeMapVisitor<K: Deserialize + Eq + Ord,
+                    V: Deserialize>,
     visitor,
     BTreeMap::new(),
-    BTreeMap::new(),
-    BTreeMap::insert);
+    BTreeMap::new());
 
 #[cfg(feature = "std")]
 map_impl!(
-    HashMap<K, V>,
-    <Deserialize, Eq, Hash>,
-    HashMapVisitor,
+    HashMap<K, V, S>,
+    HashMapVisitor<K: Deserialize + Eq + Hash,
+                   V: Deserialize,
+                   S: BuildHasher + Default>,
     visitor,
-    HashMap::new(),
-    HashMap::with_capacity(visitor.size_hint().0),
-    HashMap::insert);
+    HashMap::with_hasher(S::default()),
+    HashMap::with_capacity_and_hasher(visitor.size_hint().0, S::default()));
 
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index b51226a9..a05ae862 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -31,7 +31,7 @@ use collections::enum_set::{CLike, EnumSet};
 #[cfg(all(feature = "nightly", feature = "collections"))]
 use collections::borrow::ToOwned;
 
-use core::hash::Hash;
+use core::hash::{Hash, BuildHasher};
 #[cfg(feature = "nightly")]
 use core::iter;
 #[cfg(feature = "std")]
@@ -651,9 +651,10 @@ impl<K, V> Serialize for BTreeMap<K, V>
 }
 
 #[cfg(feature = "std")]
-impl<K, V> Serialize for HashMap<K, V>
+impl<K, V, H> Serialize for HashMap<K, V, H>
     where K: Serialize + Eq + Hash,
           V: Serialize,
+          H: BuildHasher,
 {
     #[inline]
     fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
diff --git a/serde_tests/Cargo.toml b/serde_tests/Cargo.toml
index adb7a940..47792176 100644
--- a/serde_tests/Cargo.toml
+++ b/serde_tests/Cargo.toml
@@ -19,6 +19,7 @@ syntex_syntax = { version = "^0.35.0" }
 serde_codegen = { version = "*", path = "../serde_codegen", features = ["with-syntex"] }
 
 [dev-dependencies]
+fnv = "1.0"
 rustc-serialize = "^0.3.16"
 serde = { version = "*", path = "../serde" }
 syntex = "^0.35.0"
diff --git a/serde_tests/tests/macros.rs b/serde_tests/tests/macros.rs
index 069d4f26..c0b38b3d 100644
--- a/serde_tests/tests/macros.rs
+++ b/serde_tests/tests/macros.rs
@@ -75,5 +75,13 @@ macro_rules! hashmap {
             $(map.insert($key, $value);)+
             map
         }
+    };
+    ($hasher:ident @ $($key:expr => $value:expr),+) => {
+        {
+            use std::hash::BuildHasherDefault;
+            let mut map = HashMap::with_hasher(BuildHasherDefault::<$hasher>::default());
+            $(map.insert($key, $value);)+
+            map
+        }
     }
 }
diff --git a/serde_tests/tests/test_de.rs b/serde_tests/tests/test_de.rs
index 932b4b10..8081b9ea 100644
--- a/serde_tests/tests/test_de.rs
+++ b/serde_tests/tests/test_de.rs
@@ -2,6 +2,9 @@ use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::net;
 use std::path::PathBuf;
 
+extern crate fnv;
+use self::fnv::FnvHasher;
+
 use token::{
     Error,
     Token,
@@ -532,6 +535,17 @@ declare_tests! {
             Token::StructStart("Anything", Some(0)),
             Token::MapEnd,
         ],
+        hashmap![FnvHasher @ 1 => 2, 3 => 4] => vec![
+            Token::MapStart(Some(2)),
+                Token::MapSep,
+                Token::I32(1),
+                Token::I32(2),
+
+                Token::MapSep,
+                Token::I32(3),
+                Token::I32(4),
+            Token::MapEnd,
+        ],
     }
     test_struct {
         Struct { a: 1, b: 2, c: 0 } => vec![
diff --git a/serde_tests/tests/test_ser.rs b/serde_tests/tests/test_ser.rs
index 2a8117a1..4b6e4c70 100644
--- a/serde_tests/tests/test_ser.rs
+++ b/serde_tests/tests/test_ser.rs
@@ -1,10 +1,13 @@
-use std::collections::BTreeMap;
+use std::collections::{BTreeMap, HashMap};
 use std::net;
 use std::path::{Path, PathBuf};
 use std::str;
 
 use token::{self, Token};
 
+extern crate fnv;
+use self::fnv::FnvHasher;
+
 //////////////////////////////////////////////////////////////////////////
 
 #[derive(Serialize)]
@@ -204,6 +207,19 @@ declare_ser_tests! {
             Token::MapEnd,
         ],
     }
+    test_hashmap {
+        hashmap![FnvHasher @ 1 => 2, 3 => 4] => &[
+            Token::MapStart(Some(2)),
+                Token::MapSep,
+                Token::I32(1),
+                Token::I32(2),
+
+                Token::MapSep,
+                Token::I32(3),
+                Token::I32(4),
+            Token::MapEnd,
+        ],
+    }
     test_unit_struct {
         UnitStruct => &[Token::UnitStruct("UnitStruct")],
     }