diff --git a/serde_test/src/de.rs b/serde_test/src/de.rs
index 39df2e8ca..7dc3adb09 100644
--- a/serde_test/src/de.rs
+++ b/serde_test/src/de.rs
@@ -33,10 +33,8 @@ fn unexpected(token: Token) -> Error {
     ))
 }
 
-macro_rules! end_of_tokens {
-    () => {
-        panic!("ran out of tokens to deserialize")
-    };
+fn end_of_tokens() -> Error {
+    de::Error::custom("ran out of tokens to deserialize")
 }
 
 impl<'de> Deserializer<'de> {
@@ -48,11 +46,8 @@ impl<'de> Deserializer<'de> {
         self.tokens.first().cloned()
     }
 
-    fn peek_token(&self) -> Token {
-        match self.peek_token_opt() {
-            Some(token) => token,
-            None => end_of_tokens!(),
-        }
+    fn peek_token(&self) -> Result<Token, Error> {
+        self.peek_token_opt().ok_or_else(end_of_tokens)
     }
 
     pub fn next_token_opt(&mut self) -> Option<Token> {
@@ -65,14 +60,10 @@ impl<'de> Deserializer<'de> {
         }
     }
 
-    fn next_token(&mut self) -> Token {
-        match self.tokens.split_first() {
-            Some((&first, rest)) => {
-                self.tokens = rest;
-                first
-            }
-            None => end_of_tokens!(),
-        }
+    fn next_token(&mut self) -> Result<Token, Error> {
+        let (&first, rest) = self.tokens.split_first().ok_or_else(end_of_tokens)?;
+        self.tokens = rest;
+        Ok(first)
     }
 
     pub fn remaining(&self) -> usize {
@@ -128,7 +119,7 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        let token = self.next_token();
+        let token = self.next_token()?;
         match token {
             Token::Bool(v) => visitor.visit_bool(v),
             Token::I8(v) => visitor.visit_i8(v),
@@ -160,47 +151,47 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
             Token::Map { len } => self.visit_map(len, Token::MapEnd, visitor),
             Token::Struct { len, .. } => self.visit_map(Some(len), Token::StructEnd, visitor),
             Token::Enum { .. } => {
-                let variant = self.next_token();
-                let next = self.peek_token();
+                let variant = self.next_token()?;
+                let next = self.peek_token()?;
                 match (variant, next) {
                     (Token::Str(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_str(variant)
                     }
                     (Token::BorrowedStr(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_borrowed_str(variant)
                     }
                     (Token::String(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_string(variant.to_string())
                     }
                     (Token::Bytes(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_bytes(variant)
                     }
                     (Token::BorrowedBytes(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_borrowed_bytes(variant)
                     }
                     (Token::ByteBuf(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_byte_buf(variant.to_vec())
                     }
                     (Token::U8(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_u8(variant)
                     }
                     (Token::U16(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_u16(variant)
                     }
                     (Token::U32(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_u32(variant)
                     }
                     (Token::U64(variant), Token::Unit) => {
-                        self.next_token();
+                        self.next_token()?;
                         visitor.visit_u64(variant)
                     }
                     (variant, Token::Unit) => Err(unexpected(variant)),
@@ -239,13 +230,13 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        match self.peek_token() {
+        match self.peek_token()? {
             Token::Unit | Token::None => {
-                self.next_token();
+                self.next_token()?;
                 visitor.visit_none()
             }
             Token::Some => {
-                self.next_token();
+                self.next_token()?;
                 visitor.visit_some(self)
             }
             _ => self.deserialize_any(visitor),
@@ -261,9 +252,9 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        match self.peek_token() {
+        match self.peek_token()? {
             Token::Enum { name: n } if name == n => {
-                self.next_token();
+                self.next_token()?;
 
                 visitor.visit_enum(DeserializerEnumVisitor { de: self })
             }
@@ -283,7 +274,7 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        match self.peek_token() {
+        match self.peek_token()? {
             Token::UnitStruct { .. } => {
                 assert_next_token(self, Token::UnitStruct { name: name })?;
                 visitor.visit_unit()
@@ -300,7 +291,7 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        match self.peek_token() {
+        match self.peek_token()? {
             Token::NewtypeStruct { .. } => {
                 assert_next_token(self, Token::NewtypeStruct { name: name })?;
                 visitor.visit_newtype_struct(self)
@@ -313,21 +304,21 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        match self.peek_token() {
+        match self.peek_token()? {
             Token::Unit | Token::UnitStruct { .. } => {
-                self.next_token();
+                self.next_token()?;
                 visitor.visit_unit()
             }
             Token::Seq { .. } => {
-                self.next_token();
+                self.next_token()?;
                 self.visit_seq(Some(len), Token::SeqEnd, visitor)
             }
             Token::Tuple { .. } => {
-                self.next_token();
+                self.next_token()?;
                 self.visit_seq(Some(len), Token::TupleEnd, visitor)
             }
             Token::TupleStruct { .. } => {
-                self.next_token();
+                self.next_token()?;
                 self.visit_seq(Some(len), Token::TupleStructEnd, visitor)
             }
             _ => self.deserialize_any(visitor),
@@ -343,9 +334,9 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        match self.peek_token() {
+        match self.peek_token()? {
             Token::Unit => {
-                self.next_token();
+                self.next_token()?;
                 visitor.visit_unit()
             }
             Token::UnitStruct { .. } => {
@@ -353,11 +344,11 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
                 visitor.visit_unit()
             }
             Token::Seq { .. } => {
-                self.next_token();
+                self.next_token()?;
                 self.visit_seq(Some(len), Token::SeqEnd, visitor)
             }
             Token::Tuple { .. } => {
-                self.next_token();
+                self.next_token()?;
                 self.visit_seq(Some(len), Token::TupleEnd, visitor)
             }
             Token::TupleStruct { len: n, .. } => {
@@ -377,13 +368,13 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        match self.peek_token() {
+        match self.peek_token()? {
             Token::Struct { len: n, .. } => {
                 assert_next_token(self, Token::Struct { name: name, len: n })?;
                 self.visit_map(Some(fields.len()), Token::StructEnd, visitor)
             }
             Token::Map { .. } => {
-                self.next_token();
+                self.next_token()?;
                 self.visit_map(Some(fields.len()), Token::MapEnd, visitor)
             }
             _ => self.deserialize_any(visitor),
@@ -473,7 +464,7 @@ impl<'de, 'a> EnumAccess<'de> for DeserializerEnumVisitor<'a, 'de> {
     where
         V: DeserializeSeed<'de>,
     {
-        match self.de.peek_token() {
+        match self.de.peek_token()? {
             Token::UnitVariant { variant: v, .. }
             | Token::NewtypeVariant { variant: v, .. }
             | Token::TupleVariant { variant: v, .. }
@@ -494,9 +485,9 @@ impl<'de, 'a> VariantAccess<'de> for DeserializerEnumVisitor<'a, 'de> {
     type Error = Error;
 
     fn unit_variant(self) -> Result<(), Error> {
-        match self.de.peek_token() {
+        match self.de.peek_token()? {
             Token::UnitVariant { .. } => {
-                self.de.next_token();
+                self.de.next_token()?;
                 Ok(())
             }
             _ => Deserialize::deserialize(self.de),
@@ -507,9 +498,9 @@ impl<'de, 'a> VariantAccess<'de> for DeserializerEnumVisitor<'a, 'de> {
     where
         T: DeserializeSeed<'de>,
     {
-        match self.de.peek_token() {
+        match self.de.peek_token()? {
             Token::NewtypeVariant { .. } => {
-                self.de.next_token();
+                self.de.next_token()?;
                 seed.deserialize(self.de)
             }
             _ => seed.deserialize(self.de),
@@ -520,9 +511,9 @@ impl<'de, 'a> VariantAccess<'de> for DeserializerEnumVisitor<'a, 'de> {
     where
         V: Visitor<'de>,
     {
-        match self.de.peek_token() {
+        match self.de.peek_token()? {
             Token::TupleVariant { len: enum_len, .. } => {
-                let token = self.de.next_token();
+                let token = self.de.next_token()?;
 
                 if len == enum_len {
                     self.de
@@ -534,7 +525,7 @@ impl<'de, 'a> VariantAccess<'de> for DeserializerEnumVisitor<'a, 'de> {
             Token::Seq {
                 len: Some(enum_len),
             } => {
-                let token = self.de.next_token();
+                let token = self.de.next_token()?;
 
                 if len == enum_len {
                     self.de.visit_seq(Some(len), Token::SeqEnd, visitor)
@@ -554,9 +545,9 @@ impl<'de, 'a> VariantAccess<'de> for DeserializerEnumVisitor<'a, 'de> {
     where
         V: Visitor<'de>,
     {
-        match self.de.peek_token() {
+        match self.de.peek_token()? {
             Token::StructVariant { len: enum_len, .. } => {
-                let token = self.de.next_token();
+                let token = self.de.next_token()?;
 
                 if fields.len() == enum_len {
                     self.de
@@ -568,7 +559,7 @@ impl<'de, 'a> VariantAccess<'de> for DeserializerEnumVisitor<'a, 'de> {
             Token::Map {
                 len: Some(enum_len),
             } => {
-                let token = self.de.next_token();
+                let token = self.de.next_token()?;
 
                 if fields.len() == enum_len {
                     self.de