diff --git a/serde_test/src/assert.rs b/serde_test/src/assert.rs
index 95c7b923..72116b71 100644
--- a/serde_test/src/assert.rs
+++ b/serde_test/src/assert.rs
@@ -215,7 +215,7 @@ where
 ///
 /// assert_de_tokens_error::<S>(
 ///     &[
-///         Token::Struct { name: "S", len: 1 },
+///         Token::Struct { name: "S", len: 2 },
 ///         Token::Str("x"),
 ///     ],
 ///     "unknown field `x`, expected `a` or `b`",
diff --git a/serde_test/src/de.rs b/serde_test/src/de.rs
index 015eb97f..a1074034 100644
--- a/serde_test/src/de.rs
+++ b/serde_test/src/de.rs
@@ -352,8 +352,8 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
         V: Visitor<'de>,
     {
         match self.peek_token() {
-            Token::Struct { len: n, .. } => {
-                assert_next_token!(self, Token::Struct { name: name, len: n });
+            Token::Struct { .. } => {
+                assert_next_token!(self, Token::Struct { name: name, len: fields.len() });
                 self.visit_map(Some(fields.len()), Token::StructEnd, visitor)
             }
             Token::Map { .. } => {
diff --git a/serde_test/src/token.rs b/serde_test/src/token.rs
index b8bdeb81..6c02a613 100644
--- a/serde_test/src/token.rs
+++ b/serde_test/src/token.rs
@@ -425,6 +425,10 @@ pub enum Token {
 
     /// The header of a struct.
     ///
+    /// When testing deserialization, the `len` field must match the number of
+    /// fields that the struct expects to deserialize. This may be different
+    /// from the number of fields contained in the input tokens.
+    ///
     /// After this header are the fields of the struct, followed by `StructEnd`.
     ///
     /// ```rust
@@ -461,6 +465,10 @@ pub enum Token {
 
     /// The header of a struct variant of an enum.
     ///
+    /// When testing deserialization, the `len` field must match the number of
+    /// fields that the struct variant expects to deserialize. This may be
+    /// different from the number of fields contained in the input tokens.
+    ///
     /// After this header are the fields of the struct variant, followed by
     /// `StructVariantEnd`.
     ///
diff --git a/test_suite/tests/test_annotations.rs b/test_suite/tests/test_annotations.rs
index 91719325..a175cb70 100644
--- a/test_suite/tests/test_annotations.rs
+++ b/test_suite/tests/test_annotations.rs
@@ -135,7 +135,7 @@ fn test_default_struct() {
              a5: 123,
          },
         &[
-            Token::Struct { name: "DefaultStruct", len: 1 },
+            Token::Struct { name: "DefaultStruct", len: 3 },
 
             Token::Str("a1"),
             Token::I32(1),
@@ -309,7 +309,7 @@ fn test_elt_not_deserialize() {
              c: NotDeserializeStruct(123),
              e: NotDeserializeEnum::Trouble,
          },
-        &[Token::Struct { name: "ContainsNotDeserialize", len: 3 }, Token::StructEnd],
+        &[Token::Struct { name: "ContainsNotDeserialize", len: 1 }, Token::StructEnd],
     );
 }
 
@@ -331,7 +331,7 @@ fn test_ignore_unknown() {
              a5: 123,
          },
         &[
-            Token::Struct { name: "DefaultStruct", len: 5 },
+            Token::Struct { name: "DefaultStruct", len: 3 },
 
             Token::Str("whoops1"),
             Token::I32(2),
@@ -359,7 +359,7 @@ fn test_ignore_unknown() {
 
     assert_de_tokens_error::<DenyUnknown>(
         &[
-            Token::Struct { name: "DenyUnknown", len: 2 },
+            Token::Struct { name: "DenyUnknown", len: 1 },
 
             Token::Str("a1"),
             Token::I32(1),
diff --git a/test_suite/tests/test_de.rs b/test_suite/tests/test_de.rs
index f5780936..b95b9c49 100644
--- a/test_suite/tests/test_de.rs
+++ b/test_suite/tests/test_de.rs
@@ -538,7 +538,7 @@ declare_tests! {
             Token::MapEnd,
         ],
         Struct { a: 1, b: 2, c: 0 } => &[
-            Token::Struct { name: "Struct", len: 3 },
+            Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
                 Token::I32(1),
 
@@ -570,7 +570,7 @@ declare_tests! {
             Token::MapEnd,
         ],
         Struct { a: 1, b: 2, c: 0 } => &[
-            Token::Struct { name: "Struct", len: 3 },
+            Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
                 Token::I32(1),
 
@@ -591,7 +591,7 @@ declare_tests! {
             Token::StructEnd,
         ],
         StructSkipAll { a: 0 } => &[
-            Token::Struct { name: "StructSkipAll", len: 1 },
+            Token::Struct { name: "StructSkipAll", len: 0 },
                 Token::Str("a"),
                 Token::I32(1),
 
@@ -608,7 +608,7 @@ declare_tests! {
     }
     test_struct_default {
         StructDefault { a: 50, b: "overwritten".to_string() } => &[
-            Token::Struct { name: "StructDefault", len: 1 },
+            Token::Struct { name: "StructDefault", len: 2 },
                 Token::Str("a"),
                 Token::I32(50),
 
@@ -617,7 +617,7 @@ declare_tests! {
             Token::StructEnd,
         ],
         StructDefault { a: 100, b: "default".to_string() } => &[
-            Token::Struct { name: "StructDefault",  len: 0 },
+            Token::Struct { name: "StructDefault",  len: 2 },
             Token::StructEnd,
         ],
     }
@@ -954,7 +954,7 @@ fn test_cstr_internal_null_end() {
 declare_error_tests! {
     test_unknown_field<StructDenyUnknown> {
         &[
-            Token::Struct { name: "StructDenyUnknown", len: 2 },
+            Token::Struct { name: "StructDenyUnknown", len: 1 },
                 Token::Str("a"),
                 Token::I32(0),
 
@@ -964,14 +964,14 @@ declare_error_tests! {
     }
     test_skipped_field_is_unknown<StructDenyUnknown> {
         &[
-            Token::Struct { name: "StructDenyUnknown", len: 2 },
+            Token::Struct { name: "StructDenyUnknown", len: 1 },
                 Token::Str("b"),
         ],
         "unknown field `b`, expected `a`",
     }
     test_skip_all_deny_unknown<StructSkipAllDenyUnknown> {
         &[
-            Token::Struct { name: "StructSkipAllDenyUnknown", len: 1 },
+            Token::Struct { name: "StructSkipAllDenyUnknown", len: 0 },
                 Token::Str("a"),
         ],
         "unknown field `a`, there are no fields",
diff --git a/test_suite/tests/test_macros.rs b/test_suite/tests/test_macros.rs
index 19c68382..87e86a30 100644
--- a/test_suite/tests/test_macros.rs
+++ b/test_suite/tests/test_macros.rs
@@ -786,7 +786,7 @@ fn test_adjacently_tagged_enum() {
     }
 
     // unit with no content
-    assert_tokens(
+    assert_ser_tokens(
         &AdjacentlyTagged::Unit::<u8>,
         &[
             Token::Struct { name: "AdjacentlyTagged", len: 1 },
@@ -798,11 +798,24 @@ fn test_adjacently_tagged_enum() {
         ],
     );
 
+    // unit with no content
+    assert_de_tokens(
+        &AdjacentlyTagged::Unit::<u8>,
+        &[
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
+
+            Token::Str("t"),
+            Token::Str("Unit"),
+
+            Token::StructEnd,
+        ],
+    );
+
     // unit with tag first
     assert_de_tokens(
         &AdjacentlyTagged::Unit::<u8>,
         &[
-            Token::Struct { name: "AdjacentlyTagged", len: 1 },
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
 
             Token::Str("t"),
             Token::Str("Unit"),
@@ -818,7 +831,7 @@ fn test_adjacently_tagged_enum() {
     assert_de_tokens(
         &AdjacentlyTagged::Unit::<u8>,
         &[
-            Token::Struct { name: "AdjacentlyTagged", len: 1 },
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
 
             Token::Str("c"),
             Token::Unit,
@@ -834,7 +847,7 @@ fn test_adjacently_tagged_enum() {
     assert_de_tokens(
         &AdjacentlyTagged::Unit::<u8>,
         &[
-            Token::Struct { name: "AdjacentlyTagged", len: 3 },
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
 
             Token::Str("f"),
             Token::Unit,
@@ -975,7 +988,7 @@ fn test_adjacently_tagged_enum_deny_unknown_fields() {
     assert_de_tokens(
         &AdjacentlyTagged::Unit,
         &[
-            Token::Struct { name: "AdjacentlyTagged", len: 2},
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
 
             Token::Str("t"),
             Token::Str("Unit"),
@@ -989,7 +1002,7 @@ fn test_adjacently_tagged_enum_deny_unknown_fields() {
 
     assert_de_tokens_error::<AdjacentlyTagged>(
         &[
-            Token::Struct { name: "AdjacentlyTagged", len: 3},
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
 
             Token::Str("t"),
             Token::Str("Unit"),
@@ -1004,7 +1017,7 @@ fn test_adjacently_tagged_enum_deny_unknown_fields() {
 
     assert_de_tokens_error::<AdjacentlyTagged>(
         &[
-            Token::Struct { name: "AdjacentlyTagged", len: 3},
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
 
             Token::Str("h"),
         ],
@@ -1013,7 +1026,7 @@ fn test_adjacently_tagged_enum_deny_unknown_fields() {
 
     assert_de_tokens_error::<AdjacentlyTagged>(
         &[
-            Token::Struct { name: "AdjacentlyTagged", len: 3},
+            Token::Struct { name: "AdjacentlyTagged", len: 2 },
 
             Token::Str("c"),
             Token::Unit,