diff --git a/serde/src/private/de.rs b/serde/src/private/de.rs
index bcb964a9c..808d783d0 100644
--- a/serde/src/private/de.rs
+++ b/serde/src/private/de.rs
@@ -2542,11 +2542,11 @@ pub trait IdentifierDeserializer<'de, E: Error> {
     fn from(self) -> Self::Deserializer;
 }
 
-impl<'de, E> IdentifierDeserializer<'de, E> for u32
+impl<'de, E> IdentifierDeserializer<'de, E> for u64
 where
     E: Error,
 {
-    type Deserializer = <u32 as IntoDeserializer<'de, E>>::Deserializer;
+    type Deserializer = <u64 as IntoDeserializer<'de, E>>::Deserializer;
 
     fn from(self) -> Self::Deserializer {
         self.into_deserializer()
diff --git a/serde_derive/src/de.rs b/serde_derive/src/de.rs
index 1f5733a6d..3267a3e5f 100644
--- a/serde_derive/src/de.rs
+++ b/serde_derive/src/de.rs
@@ -1940,6 +1940,15 @@ fn deserialize_generated_identifier(
     }
 }
 
+/// Generates `Deserialize::deserialize` body for
+/// ```ignore
+/// #[serde(field_identifier)]
+/// enum Field {
+/// }
+/// #[serde(variant_identifier)]
+/// enum Variant {
+/// }
+/// ```
 fn deserialize_custom_identifier(
     params: &Parameters,
     variants: &[Variant],
@@ -1957,6 +1966,8 @@ fn deserialize_custom_identifier(
     let (ordinary, fallthrough) = if let Some(last) = variants.last() {
         let last_ident = &last.ident;
         if last.attrs.other() {
+            // Processes `#[serde(other)]` attribute. It always belongs to the last variant
+            // (checked in `check_identifier`), so all other are ordinal variants
             let ordinary = &variants[..variants.len() - 1];
             let fallthrough = quote!(_serde::export::Ok(#this::#last_ident));
             (ordinary, Some(fallthrough))
@@ -1976,6 +1987,10 @@ fn deserialize_custom_identifier(
         (variants, None)
     };
 
+    // List of tuples:
+    // - field or variant name in the expected messages
+    // - information about field/variant
+    // - list of alternate names of the field/variant
     let names_idents: Vec<_> = ordinary
         .iter()
         .map(|variant| {
@@ -2106,7 +2121,7 @@ fn deserialize_identifier(
         (None, None, None, None)
     };
 
-    let fallthrough_arm = if let Some(fallthrough) = fallthrough {
+    let fallthrough_arm = if let Some(fallthrough) = fallthrough.clone() {
         fallthrough
     } else if is_variant {
         quote! {
@@ -2118,8 +2133,19 @@ fn deserialize_identifier(
         }
     };
 
+    let u64_fallthrough_arm = if let Some(fallthrough) = fallthrough {
+        fallthrough
+    } else {
+        let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
+        quote! {
+            _serde::export::Err(_serde::de::Error::invalid_value(
+                _serde::de::Unexpected::Unsigned(__value),
+                &#fallthrough_msg,
+            ))
+        }
+    };
+
     let variant_indices = 0_u64..;
-    let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
     let visit_other = if collect_other_fields {
         quote! {
             fn visit_bool<__E>(self, __value: bool) -> _serde::export::Result<Self::Value, __E>
@@ -2254,10 +2280,9 @@ fn deserialize_identifier(
                     #(
                         #variant_indices => _serde::export::Ok(#main_constructors),
                     )*
-                    _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                        _serde::de::Unexpected::Unsigned(__value),
-                        &#fallthrough_msg,
-                    ))
+                    _ => {
+                        #u64_fallthrough_arm
+                    }
                 }
             }
         }
diff --git a/serde_test/src/de.rs b/serde_test/src/de.rs
index c9bcee5b3..5113b2910 100644
--- a/serde_test/src/de.rs
+++ b/serde_test/src/de.rs
@@ -168,14 +168,42 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
                         self.next_token();
                         visitor.visit_str(variant)
                     }
+                    (Token::BorrowedStr(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_borrowed_str(variant)
+                    }
+                    (Token::String(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_string(variant.to_string())
+                    }
                     (Token::Bytes(variant), Token::Unit) => {
                         self.next_token();
                         visitor.visit_bytes(variant)
                     }
+                    (Token::BorrowedBytes(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_borrowed_bytes(variant)
+                    }
+                    (Token::ByteBuf(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_byte_buf(variant.to_vec())
+                    }
+                    (Token::U8(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u8(variant)
+                    }
+                    (Token::U16(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u16(variant)
+                    }
                     (Token::U32(variant), Token::Unit) => {
                         self.next_token();
                         visitor.visit_u32(variant)
                     }
+                    (Token::U64(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u64(variant)
+                    }
                     (variant, Token::Unit) => unexpected!(variant),
                     (variant, _) => {
                         visitor.visit_map(EnumMapVisitor::new(self, variant, EnumFormat::Any))
diff --git a/test_suite/tests/expand/de_enum.expanded.rs b/test_suite/tests/expand/de_enum.expanded.rs
index a4ba24911..3fad0ded4 100644
--- a/test_suite/tests/expand/de_enum.expanded.rs
+++ b/test_suite/tests/expand/de_enum.expanded.rs
@@ -563,10 +563,7 @@ const _: () = {
                                         1u64 => _serde::export::Ok(__Field::__field1),
                                         2u64 => _serde::export::Ok(__Field::__field2),
                                         3u64 => _serde::export::Ok(__Field::__field3),
-                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                                            _serde::de::Unexpected::Unsigned(__value),
-                                            &"field index 0 <= i < 4",
-                                        )),
+                                        _ => _serde::export::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
@@ -1066,10 +1063,7 @@ const _: () = {
                                         1u64 => _serde::export::Ok(__Field::__field1),
                                         2u64 => _serde::export::Ok(__Field::__field2),
                                         3u64 => _serde::export::Ok(__Field::__field3),
-                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                                            _serde::de::Unexpected::Unsigned(__value),
-                                            &"field index 0 <= i < 4",
-                                        )),
+                                        _ => _serde::export::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
diff --git a/test_suite/tests/expand/default_ty_param.expanded.rs b/test_suite/tests/expand/default_ty_param.expanded.rs
index 8aaa3ab43..ee0f0666f 100644
--- a/test_suite/tests/expand/default_ty_param.expanded.rs
+++ b/test_suite/tests/expand/default_ty_param.expanded.rs
@@ -74,10 +74,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::export::Ok(__Field::__field0),
-                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::export::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
@@ -250,10 +247,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::export::Ok(__Field::__field0),
-                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::export::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
diff --git a/test_suite/tests/expand/generic_enum.expanded.rs b/test_suite/tests/expand/generic_enum.expanded.rs
index add7c510d..88f441b33 100644
--- a/test_suite/tests/expand/generic_enum.expanded.rs
+++ b/test_suite/tests/expand/generic_enum.expanded.rs
@@ -347,10 +347,7 @@ const _: () = {
                                     match __value {
                                         0u64 => _serde::export::Ok(__Field::__field0),
                                         1u64 => _serde::export::Ok(__Field::__field1),
-                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                                            _serde::de::Unexpected::Unsigned(__value),
-                                            &"field index 0 <= i < 2",
-                                        )),
+                                        _ => _serde::export::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
diff --git a/test_suite/tests/expand/generic_struct.expanded.rs b/test_suite/tests/expand/generic_struct.expanded.rs
index 59d2e51d7..ea3059de0 100644
--- a/test_suite/tests/expand/generic_struct.expanded.rs
+++ b/test_suite/tests/expand/generic_struct.expanded.rs
@@ -70,10 +70,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::export::Ok(__Field::__field0),
-                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::export::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
@@ -246,10 +243,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::export::Ok(__Field::__field0),
-                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::export::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
diff --git a/test_suite/tests/expand/lifetimes.expanded.rs b/test_suite/tests/expand/lifetimes.expanded.rs
index 9840d4401..bab22ebe0 100644
--- a/test_suite/tests/expand/lifetimes.expanded.rs
+++ b/test_suite/tests/expand/lifetimes.expanded.rs
@@ -235,10 +235,7 @@ const _: () = {
                                 {
                                     match __value {
                                         0u64 => _serde::export::Ok(__Field::__field0),
-                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                                            _serde::de::Unexpected::Unsigned(__value),
-                                            &"field index 0 <= i < 1",
-                                        )),
+                                        _ => _serde::export::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
@@ -420,10 +417,7 @@ const _: () = {
                                 {
                                     match __value {
                                         0u64 => _serde::export::Ok(__Field::__field0),
-                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                                            _serde::de::Unexpected::Unsigned(__value),
-                                            &"field index 0 <= i < 1",
-                                        )),
+                                        _ => _serde::export::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
diff --git a/test_suite/tests/expand/named_map.expanded.rs b/test_suite/tests/expand/named_map.expanded.rs
index ce43b6634..b35da6831 100644
--- a/test_suite/tests/expand/named_map.expanded.rs
+++ b/test_suite/tests/expand/named_map.expanded.rs
@@ -97,10 +97,7 @@ const _: () = {
                         0u64 => _serde::export::Ok(__Field::__field0),
                         1u64 => _serde::export::Ok(__Field::__field1),
                         2u64 => _serde::export::Ok(__Field::__field2),
-                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 3",
-                        )),
+                        _ => _serde::export::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
@@ -373,10 +370,7 @@ const _: () = {
                         0u64 => _serde::export::Ok(__Field::__field0),
                         1u64 => _serde::export::Ok(__Field::__field1),
                         2u64 => _serde::export::Ok(__Field::__field2),
-                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 3",
-                        )),
+                        _ => _serde::export::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
diff --git a/test_suite/tests/test_de.rs b/test_suite/tests/test_de.rs
index 025d87b09..3a41a6828 100644
--- a/test_suite/tests/test_de.rs
+++ b/test_suite/tests/test_de.rs
@@ -622,6 +622,24 @@ declare_tests! {
                 Token::I32(2),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U8(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U16(0),
+                Token::I32(1),
+
+                Token::U16(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Map { len: Some(3) },
                 Token::U32(0),
@@ -631,6 +649,34 @@ declare_tests! {
                 Token::I32(2),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U64(0),
+                Token::I32(1),
+
+                Token::U64(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        // Mixed key types
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U64(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::Str("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
@@ -647,6 +693,46 @@ declare_tests! {
             Token::SeqEnd,
         ],
     }
+    test_struct_borrowed_keys {
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::BorrowedStr("a"),
+                Token::I32(1),
+
+                Token::BorrowedStr("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Struct { name: "Struct", len: 2 },
+                Token::BorrowedStr("a"),
+                Token::I32(1),
+
+                Token::BorrowedStr("b"),
+                Token::I32(2),
+            Token::StructEnd,
+        ],
+    }
+    test_struct_owned_keys {
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::String("a"),
+                Token::I32(1),
+
+                Token::String("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Struct { name: "Struct", len: 2 },
+                Token::String("a"),
+                Token::I32(1),
+
+                Token::String("b"),
+                Token::I32(2),
+            Token::StructEnd,
+        ],
+    }
     test_struct_with_skip {
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Map { len: Some(3) },
@@ -663,6 +749,21 @@ declare_tests! {
                 Token::I32(4),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U16(1),
+                Token::I32(2),
+
+                Token::U32(2),
+                Token::I32(3),
+
+                Token::U64(3),
+                Token::I32(4),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
@@ -780,6 +881,26 @@ declare_tests! {
             Token::Str("Unit"),
             Token::Unit,
         ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U8(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U16(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U32(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U64(0),
+            Token::Unit,
+        ],
     }
     test_enum_other {
         EnumOther::Other => &[
@@ -787,6 +908,26 @@ declare_tests! {
             Token::Str("Foo"),
             Token::Unit,
         ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U8(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U16(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U32(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U64(42),
+            Token::Unit,
+        ],
     }
     test_box {
         Box::new(0i32) => &[Token::I32(0)],
diff --git a/test_suite/tests/test_identifier.rs b/test_suite/tests/test_identifier.rs
index eba7d4dac..12c6697e6 100644
--- a/test_suite/tests/test_identifier.rs
+++ b/test_suite/tests/test_identifier.rs
@@ -1,3 +1,4 @@
+//! Tests for `#[serde(field_identifier)]` and `#[serde(variant_identifier)]`
 use serde::Deserialize;
 use serde_test::{assert_de_tokens, Token};
 
@@ -27,6 +28,10 @@ fn test_field_identifier() {
         Bbb,
     }
 
+    assert_de_tokens(&F::Aaa, &[Token::U8(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U16(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U32(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U64(0)]);
     assert_de_tokens(&F::Aaa, &[Token::Str("aaa")]);
     assert_de_tokens(&F::Aaa, &[Token::Bytes(b"aaa")]);
 }
@@ -42,6 +47,10 @@ fn test_unit_fallthrough() {
         Other,
     }
 
+    assert_de_tokens(&F::Other, &[Token::U8(42)]);
+    assert_de_tokens(&F::Other, &[Token::U16(42)]);
+    assert_de_tokens(&F::Other, &[Token::U32(42)]);
+    assert_de_tokens(&F::Other, &[Token::U64(42)]);
     assert_de_tokens(&F::Other, &[Token::Str("x")]);
 }
 
@@ -68,5 +77,9 @@ fn test_newtype_fallthrough_generic() {
         Other(T),
     }
 
+    assert_de_tokens(&F::Other(42u8), &[Token::U8(42)]);
+    assert_de_tokens(&F::Other(42u16), &[Token::U16(42)]);
+    assert_de_tokens(&F::Other(42u32), &[Token::U32(42)]);
+    assert_de_tokens(&F::Other(42u64), &[Token::U64(42)]);
     assert_de_tokens(&F::Other("x".to_owned()), &[Token::Str("x")]);
 }