diff --git a/examples/read_buffered.rs b/examples/read_buffered.rs
new file mode 100644
index 00000000..25b28ee2
--- /dev/null
+++ b/examples/read_buffered.rs
@@ -0,0 +1,34 @@
+// This example demonstrates how a reader (for example when reading from a file)
+// can be buffered. In that case, data read from the file is written to a supplied
+// buffer and returned XML events borrow from that buffer.
+// That way, allocations can be kept to a minimum.
+
+fn main() -> Result<(), quick_xml::Error> {
+    use quick_xml::events::Event;
+    use quick_xml::Reader;
+
+    let mut reader = Reader::from_file("tests/documents/document.xml")?;
+    reader.trim_text(true);
+
+    let mut buf = Vec::new();
+
+    let mut count = 0;
+
+    loop {
+        match reader.read_event_into(&mut buf) {
+            Ok(Event::Start(ref e)) => {
+                let name = e.name();
+                let name = reader.decoder().decode(name.as_ref())?;
+                println!("read start event {:?}", name.as_ref());
+                count += 1;
+            }
+            Ok(Event::Eof) => break, // exits the loop when reaching end of file
+            Err(e) => panic!("Error at position {}: {:?}", reader.buffer_position(), e),
+            _ => (), // There are several other `Event`s we do not consider here
+        }
+    }
+
+    println!("read {} start events in total", count);
+
+    Ok(())
+}
diff --git a/src/reader/buffered_reader.rs b/src/reader/buffered_reader.rs
index c86f5ace..66765b64 100644
--- a/src/reader/buffered_reader.rs
+++ b/src/reader/buffered_reader.rs
@@ -238,6 +238,9 @@ impl<'b, R: BufRead> XmlSource<'b, &'b mut Vec<u8>> for R {
         buf: &'b mut Vec<u8>,
         position: &mut usize,
     ) -> Result<Option<&'b [u8]>> {
+        // search byte must be within the ascii range
+        debug_assert!(byte.is_ascii());
+
         let mut read = 0;
         let mut done = false;
         let start = buf.len();
@@ -397,6 +400,9 @@ impl<'b, R: BufRead> XmlSource<'b, &'b mut Vec<u8>> for R {
     /// Consume and discard one character if it matches the given byte. Return
     /// true if it matched.
     fn skip_one(&mut self, byte: u8, position: &mut usize) -> Result<bool> {
+        // search byte must be within the ascii range
+        debug_assert!(byte.is_ascii());
+
         match self.peek_one()? {
             Some(b) if b == byte => {
                 *position += 1;
diff --git a/src/reader/slice_reader.rs b/src/reader/slice_reader.rs
index 0a71f050..6cedfe2f 100644
--- a/src/reader/slice_reader.rs
+++ b/src/reader/slice_reader.rs
@@ -147,6 +147,8 @@ impl<'a> XmlSource<'a, ()> for &'a [u8] {
         _buf: (),
         position: &mut usize,
     ) -> Result<Option<&'a [u8]>> {
+        // search byte must be within the ascii range
+        debug_assert!(byte.is_ascii());
         if self.is_empty() {
             return Ok(None);
         }
@@ -217,6 +219,8 @@ impl<'a> XmlSource<'a, ()> for &'a [u8] {
     }
 
     fn skip_one(&mut self, byte: u8, position: &mut usize) -> Result<bool> {
+        // search byte must be within the ascii range
+        debug_assert!(byte.is_ascii());
         if self.first() == Some(&byte) {
             *self = &self[1..];
             *position += 1;