diff --git a/instant-xml-macros/src/de.rs b/instant-xml-macros/src/de.rs
index db291c4..979f25b 100644
--- a/instant-xml-macros/src/de.rs
+++ b/instant-xml-macros/src/de.rs
@@ -272,8 +272,8 @@ impl Deserializer {
         ));
 
         let def_prefix = match def_prefix {
-            Some(def_prefix) => quote!(let def_prefix: Option<&str> = Some(#def_prefix);),
-            None => quote!(let def_prefix: Option<&str> = None;),
+            Some(def_prefix) => quote!(Some(#def_prefix)),
+            None => quote!(None::<&str>),
         };
 
         let field_namespace = match field_namespace {
@@ -290,33 +290,7 @@ impl Deserializer {
                         panic!("duplicated value");
                     }
 
-                    match item.prefix {
-                        Some(item) => {
-                            let parser_prefix = item.to_owned();
-                            #def_prefix
-                            match def_prefix {
-                                Some(def_prefix) => {
-                                    // Check if defined and gotten namespaces equals for each field
-                                    if deserializer.get_parser_namespace(&parser_prefix)
-                                        != deserializer.get_def_namespace(def_prefix) {
-                                        return Err(Error::WrongNamespace)
-                                    }
-                                }
-                                None => {
-                                    return Err(Error::WrongNamespace);
-                                }
-                            }
-                        }
-                        None => {
-                            #def_prefix
-                            match def_prefix {
-                                Some(_) => {
-                                    return Err(Error::WrongNamespace)
-                                },
-                                None => (),
-                            }
-                        }
-                    }
+                    deserializer.compare_namespace(&item.prefix, #def_prefix)?;
                     #field_namespace
                     deserializer.set_next_def_namespace(field_namespace)?;
                     #enum_name = Some(<#no_lifetime_type>::deserialize(deserializer)?);
diff --git a/instant-xml/src/lib.rs b/instant-xml/src/lib.rs
index 7c393f4..acc4d57 100644
--- a/instant-xml/src/lib.rs
+++ b/instant-xml/src/lib.rs
@@ -242,12 +242,22 @@ impl<'xml> Deserializer<'xml> {
         self.parser.peek_next_tag()
     }
 
-    pub fn get_def_namespace(&self, prefix: &str) -> Option<&&str> {
-        self.def_namespaces.get(prefix)
-    }
-
-    pub fn get_parser_namespace(&self, prefix: &str) -> Option<&&str> {
-        self.parser_namespaces.get(prefix)
+    // Check if defined and gotten namespaces equals for each field
+    pub fn compare_namespace(
+        &self,
+        expected: &Option<&str>,
+        actual: Option<&str>,
+    ) -> Result<(), Error> {
+        match (expected, actual) {
+            (Some(expected), Some(actual)) => {
+                match self.parser_namespaces.get(expected) == self.def_namespaces.get(actual) {
+                    true => Ok(()),
+                    false => Err(Error::WrongNamespace),
+                }
+            }
+            (Some(_), None) | (None, Some(_)) => Err(Error::WrongNamespace),
+            (None, None) => Ok(()),
+        }
     }
 
     pub fn compare_parser_and_def_default_namespaces(&self) -> bool {