diff --git a/src/maven/pom_reader.rs b/src/maven/pom_reader.rs
index 7e70033..35211a6 100644
--- a/src/maven/pom_reader.rs
+++ b/src/maven/pom_reader.rs
@@ -21,11 +21,7 @@ impl SaxHandler for PomReader{
     fn start_prefix_mapping(&mut self, prefix: &str, uri: &str) {
         todo!()
     }
-
-    fn end_prefix_mapping(&mut self, prefix: &str, uri: &str) {
-        todo!()
-    }
-
+    
     fn start_element(&mut self, uri: Option<String>, local_name: &str, qualified_name: &str, attributes: Vec<Attribute>) {
         todo!()
     }
diff --git a/src/xml/debug.rs b/src/xml/debug.rs
index 89030b0..e0591e7 100644
--- a/src/xml/debug.rs
+++ b/src/xml/debug.rs
@@ -10,12 +10,10 @@ impl SaxHandler for DebugHandler {
     fn end_document(&mut self) {
         debug!("end_document");
     }
-    fn start_prefix_mapping(&mut self, _prefix: &str, _uri: &str) {
-        debug!("start_prefix_mapping");
-    }
-    fn end_prefix_mapping(&mut self, _prefix: &str, _uri: &str) {
-        debug!("end_prefix_mapping");
+    fn start_prefix_mapping(&mut self, prefix: &str, _uri: &str) {
+        debug!("start_prefix_mapping for {}", prefix);
     }
+
     fn start_element(
         &mut self,
         _uri: Option<String>,
diff --git a/src/xml/mod.rs b/src/xml/mod.rs
index 8c9af14..fef7bb1 100644
--- a/src/xml/mod.rs
+++ b/src/xml/mod.rs
@@ -12,7 +12,6 @@ pub trait SaxHandler {
     fn start_document(&mut self);
     fn end_document(&mut self);
     fn start_prefix_mapping(&mut self, prefix: &str, uri: &str);
-    fn end_prefix_mapping(&mut self, prefix: &str, uri: &str);
     fn start_element(
         &mut self,
         uri: Option<String>,
diff --git a/src/xml/sax_parser.rs b/src/xml/sax_parser.rs
index 2f0c3ea..492f8ae 100644
--- a/src/xml/sax_parser.rs
+++ b/src/xml/sax_parser.rs
@@ -110,7 +110,7 @@ impl<'a> SAXParser<'a> {
             (None, qname)
         };
 
-        let qualified_name = if let Some(namespace) = &namespace{
+        let qualified_name = if let Some(namespace) = &namespace {
             &format!("{}:{}", namespace.clone(), &lname)
         } else {
             &lname
@@ -123,7 +123,8 @@ impl<'a> SAXParser<'a> {
         if self.current == '/' {
             self.advance()?;
             let namespace = self.pop_namespace();
-            self.handler.end_element(namespace, lname.as_str(), qualified_name);
+            self.handler
+                .end_element(namespace, lname.as_str(), qualified_name);
         }
         self.expect_char('>')?;
         self.skip_whitespace()?;
@@ -139,7 +140,10 @@ impl<'a> SAXParser<'a> {
 
         if att_name.starts_with("xmlns:") {
             let prefix = att_name[6..].to_string();
-            self.prefix_mapping.insert(prefix, att_value.to_string());
+            self.prefix_mapping
+                .insert(prefix.clone(), att_value.to_string());
+            self.handler
+                .start_prefix_mapping(&prefix, &att_value);
         }
 
         let namespace = if att_name == "xmlns" {
diff --git a/tests/xml/sax_parser_test.rs b/tests/xml/sax_parser_test.rs
index d77bc63..b229229 100644
--- a/tests/xml/sax_parser_test.rs
+++ b/tests/xml/sax_parser_test.rs
@@ -1,3 +1,4 @@
+use std::collections::HashMap;
 use undeepend::xml::sax_parser::parse_string;
 use undeepend::xml::{Attribute, SaxError, SaxHandler};
 
@@ -120,10 +121,16 @@ fn test_namespace_prefixes() {
         testhandler.elements[2],
         r#"<http://example.com/books:page>"#
     );
-    assert_eq!(testhandler.elements[3], r#"<http://example.com/covers:cover>"#);
+    assert_eq!(
+        testhandler.elements[3],
+        r#"<http://example.com/covers:cover>"#
+    );
     assert_eq!(testhandler.elements[4], r#"<publisher>"#);
     assert_eq!(testhandler.end_element_called, 5);
     assert_eq!(testhandler.end_document_called, 1);
+    assert_eq!(testhandler.mappings.len(), 2);
+    assert_eq!(testhandler.mappings["books"], "http://example.com/books");
+    assert_eq!(testhandler.mappings["covers"], "http://example.com/covers");
 }
 
 #[derive(Debug)]
@@ -133,6 +140,7 @@ struct TestHandler {
     start_element_called: usize,
     end_element_called: usize,
     elements: Vec<String>,
+    mappings: HashMap<String, String>,
 }
 
 impl TestHandler {
@@ -143,6 +151,7 @@ impl TestHandler {
             start_element_called: 0,
             end_element_called: 0,
             elements: vec![],
+            mappings: HashMap::new(),
         }
     }
 }
@@ -156,12 +165,8 @@ impl SaxHandler for TestHandler {
         self.end_document_called += 1;
     }
 
-    fn start_prefix_mapping(&mut self, _prefix: &str, _uri: &str) {
-        todo!()
-    }
-
-    fn end_prefix_mapping(&mut self, _prefix: &str, _uri: &str) {
-        todo!()
+    fn start_prefix_mapping(&mut self, prefix: &str, uri: &str) {
+        self.mappings.insert(prefix.to_string(), uri.to_string());
     }
 
     fn start_element(