diff --git a/src/lib.rs b/src/lib.rs
index fe8c61491..f3c9c0e33 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -819,7 +819,7 @@ pub mod tests {
     fn test_indexedfield_not_in_documents() -> crate::Result<()> {
         let mut schema_builder = Schema::builder();
         let text_field = schema_builder.add_text_field("text", TEXT);
-        let absent_field = schema_builder.add_text_field("text", TEXT);
+        let absent_field = schema_builder.add_text_field("absent_text", TEXT);
         let schema = schema_builder.build();
         let index = Index::create_in_ram(schema);
         let mut index_writer = index.writer_for_tests()?;
@@ -1001,7 +1001,7 @@ pub mod tests {
         let fast_field_signed = schema_builder.add_i64_field("signed", FAST);
         let fast_field_float = schema_builder.add_f64_field("float", FAST);
         let text_field = schema_builder.add_text_field("text", TEXT);
-        let stored_int_field = schema_builder.add_u64_field("text", STORED);
+        let stored_int_field = schema_builder.add_u64_field("stored_int", STORED);
         let schema = schema_builder.build();
 
         let index = Index::create_in_ram(schema);
diff --git a/src/query/set_query.rs b/src/query/set_query.rs
index 002e6cbd6..7029945dd 100644
--- a/src/query/set_query.rs
+++ b/src/query/set_query.rs
@@ -115,7 +115,7 @@ mod tests {
     pub fn test_term_set_query() -> crate::Result<()> {
         let mut schema_builder = Schema::builder();
         let field1 = schema_builder.add_text_field("field1", TEXT);
-        let field2 = schema_builder.add_text_field("field1", TEXT);
+        let field2 = schema_builder.add_text_field("field2", TEXT);
         let schema = schema_builder.build();
         let index = Index::create_in_ram(schema);
         {
diff --git a/src/schema/schema.rs b/src/schema/schema.rs
index 3b7fd22d0..0650a78f2 100644
--- a/src/schema/schema.rs
+++ b/src/schema/schema.rs
@@ -46,13 +46,9 @@ impl SchemaBuilder {
     /// Adds a new u64 field.
     /// Returns the associated field handle
     ///
-    /// # Caution
+    /// # Panics
     ///
-    /// Appending two fields with the same name
-    /// will result in the shadowing of the first
-    /// by the second one.
-    /// The first field will get a field id
-    /// but only the second one will be indexed
+    /// Panics when field already exists.
     pub fn add_u64_field<T: Into<NumericOptions>>(
         &mut self,
         field_name_str: &str,
@@ -66,13 +62,9 @@ impl SchemaBuilder {
     /// Adds a new i64 field.
     /// Returns the associated field handle
     ///
-    /// # Caution
+    /// # Panics
     ///
-    /// Appending two fields with the same name
-    /// will result in the shadowing of the first
-    /// by the second one.
-    /// The first field will get a field id
-    /// but only the second one will be indexed
+    /// Panics when field already exists.
     pub fn add_i64_field<T: Into<NumericOptions>>(
         &mut self,
         field_name_str: &str,
@@ -86,13 +78,9 @@ impl SchemaBuilder {
     /// Adds a new f64 field.
     /// Returns the associated field handle
     ///
-    /// # Caution
+    /// # Panics
     ///
-    /// Appending two fields with the same name
-    /// will result in the shadowing of the first
-    /// by the second one.
-    /// The first field will get a field id
-    /// but only the second one will be indexed
+    /// Panics when field already exists.
     pub fn add_f64_field<T: Into<NumericOptions>>(
         &mut self,
         field_name_str: &str,
@@ -106,13 +94,9 @@ impl SchemaBuilder {
     /// Adds a new bool field.
     /// Returns the associated field handle
     ///
-    /// # Caution
+    /// # Panics
     ///
-    /// Appending two fields with the same name
-    /// will result in the shadowing of the first
-    /// by the second one.
-    /// The first field will get a field id
-    /// but only the second one will be indexed
+    /// Panics when field already exists.
     pub fn add_bool_field<T: Into<NumericOptions>>(
         &mut self,
         field_name_str: &str,
@@ -128,13 +112,9 @@ impl SchemaBuilder {
     /// Internally, Tantivy simply stores dates as i64 UTC timestamps,
     /// while the user supplies DateTime values for convenience.
     ///
-    /// # Caution
+    /// # Panics
     ///
-    /// Appending two fields with the same name
-    /// will result in the shadowing of the first
-    /// by the second one.
-    /// The first field will get a field id
-    /// but only the second one will be indexed
+    /// Panics when field already exists.
     pub fn add_date_field<T: Into<DateOptions>>(
         &mut self,
         field_name_str: &str,
@@ -148,13 +128,9 @@ impl SchemaBuilder {
     /// Adds a ip field.
     /// Returns the associated field handle.
     ///
-    /// # Caution
+    /// # Panics
     ///
-    /// Appending two fields with the same name
-    /// will result in the shadowing of the first
-    /// by the second one.
-    /// The first field will get a field id
-    /// but only the second one will be indexed
+    /// Panics when field already exists.
     pub fn add_ip_addr_field<T: Into<IpAddrOptions>>(
         &mut self,
         field_name_str: &str,
@@ -168,13 +144,9 @@ impl SchemaBuilder {
     /// Adds a new text field.
     /// Returns the associated field handle
     ///
-    /// # Caution
+    /// # Panics
     ///
-    /// Appending two fields with the same name
-    /// will result in the shadowing of the first
-    /// by the second one.
-    /// The first field will get a field id
-    /// but only the second one will be indexed
+    /// Panics when field already exists.
     pub fn add_text_field<T: Into<TextOptions>>(
         &mut self,
         field_name_str: &str,
@@ -228,8 +200,10 @@ impl SchemaBuilder {
     pub fn add_field(&mut self, field_entry: FieldEntry) -> Field {
         let field = Field::from_field_id(self.fields.len() as u32);
         let field_name = field_entry.name().to_string();
+        if let Some(_previous_value) = self.fields_map.insert(field_name, field) {
+            panic!("Field already exists in schema {}", field_entry.name());
+        };
         self.fields.push(field_entry);
-        self.fields_map.insert(field_name, field);
         field
     }