diff --git a/.travis.yml b/.travis.yml
index c0302f0..dc0fd34 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,10 +2,12 @@ language: rust
 rust:
   - 1.36.0
   - 1.37.0
-  - 1.38.0
-  - 1.39.0
+  # error on cfg(doctest)
+  # - 1.38.0
+  # - 1.39.0
   - 1.40.0
   - 1.41.0
+  - 1.42.0
   - stable
   - beta
   - nightly
@@ -22,6 +24,8 @@ matrix:
         - cargo fmt --version
       script:
         - cargo fmt -- --check
+      env:
+        - CHECK_FORMAT=true
 
     # Clippy
     - rust: stable
@@ -30,6 +34,8 @@ matrix:
       script:
         # Fail if clippy output contains "error:" or "warning:"
         - cargo clippy 2>&1 | tee ./clippy.out && ! grep -qe  "error:\|warning:" ./clippy.out
+      env:
+        - CHECK_SYNTAX=true
 
     # Test coverage (with Tarpaulin)
     - rust: stable
@@ -39,6 +45,8 @@ matrix:
         - RUSTFLAGS="--cfg procmacro2_semver_exempt" cargo install cargo-tarpaulin --force
       script:
         - cargo tarpaulin -v --ciserver travis-ci --coveralls $TRAVIS_JOB_ID
+      env:
+        - COVERAGE_MEASUREMENT=true
 
 script:
   - cargo test
diff --git a/yaserde/Cargo.toml b/yaserde/Cargo.toml
index 316759f..63b740b 100644
--- a/yaserde/Cargo.toml
+++ b/yaserde/Cargo.toml
@@ -9,6 +9,7 @@ repository = "https://github.com/media-io/yaserde"
 homepage = "https://github.com/media-io/yaserde"
 documentation = "https://docs.rs/yaserde"
 readme = "../README.md"
+edition = "2018"
 
 [dependencies]
 yaserde_derive = { version = "0.3.11", path = "../yaserde_derive", optional = true }
diff --git a/yaserde/src/de/mod.rs b/yaserde/src/de/mod.rs
index d696092..a894d28 100644
--- a/yaserde/src/de/mod.rs
+++ b/yaserde/src/de/mod.rs
@@ -1,10 +1,10 @@
 //! Generic data structure deserialization framework.
 //!
 
+use crate::YaDeserialize;
 use std::io::Read;
 use xml::name::OwnedName;
 use xml::reader::{EventReader, ParserConfig, XmlEvent};
-use YaDeserialize;
 
 pub fn from_str<T: YaDeserialize>(s: &str) -> Result<T, String> {
   from_reader(s.as_bytes())
diff --git a/yaserde/src/lib.rs b/yaserde/src/lib.rs
index d01ce51..8796731 100644
--- a/yaserde/src/lib.rs
+++ b/yaserde/src/lib.rs
@@ -5,7 +5,7 @@
 
 #[macro_use]
 extern crate log;
-extern crate xml;
+
 #[cfg(feature = "yaserde_derive")]
 #[allow(unused_imports)]
 #[macro_use]
diff --git a/yaserde/src/ser/mod.rs b/yaserde/src/ser/mod.rs
index 3366e21..510099d 100644
--- a/yaserde/src/ser/mod.rs
+++ b/yaserde/src/ser/mod.rs
@@ -1,12 +1,12 @@
 //! Generic data structure serialization framework.
 //!
 
+use crate::YaSerialize;
 use std::io::{Cursor, Write};
 use std::str;
 use xml;
 use xml::writer::XmlEvent;
 use xml::{EmitterConfig, EventWriter};
-use YaSerialize;
 
 pub fn to_string<T: YaSerialize>(model: &T) -> Result<String, String> {
   let buf = Cursor::new(Vec::new());
diff --git a/yaserde/tests/de_default.rs b/yaserde/tests/de_default.rs
index 5654062..bb0c406 100644
--- a/yaserde/tests/de_default.rs
+++ b/yaserde/tests/de_default.rs
@@ -1,8 +1,4 @@
 #[macro_use]
-extern crate log;
-extern crate xml;
-extern crate yaserde;
-#[macro_use]
 extern crate yaserde_derive;
 
 use std::io::Read;
diff --git a/yaserde/tests/de_namespace.rs b/yaserde/tests/de_namespace.rs
index d07d8a9..dd3d94c 100644
--- a/yaserde/tests/de_namespace.rs
+++ b/yaserde/tests/de_namespace.rs
@@ -1,8 +1,4 @@
 #[macro_use]
-extern crate log;
-extern crate xml;
-extern crate yaserde;
-#[macro_use]
 extern crate yaserde_derive;
 
 use std::io::Read;
diff --git a/yaserde/tests/de_option.rs b/yaserde/tests/de_option.rs
index 7167885..a986ce4 100644
--- a/yaserde/tests/de_option.rs
+++ b/yaserde/tests/de_option.rs
@@ -1,8 +1,4 @@
 #[macro_use]
-extern crate log;
-extern crate xml;
-extern crate yaserde;
-#[macro_use]
 extern crate yaserde_derive;
 
 use std::io::Read;
diff --git a/yaserde/tests/de_type.rs b/yaserde/tests/de_type.rs
index e6f82d1..b8775da 100644
--- a/yaserde/tests/de_type.rs
+++ b/yaserde/tests/de_type.rs
@@ -1,8 +1,4 @@
 #[macro_use]
-extern crate log;
-extern crate xml;
-extern crate yaserde;
-#[macro_use]
 extern crate yaserde_derive;
 
 use std::io::Read;
diff --git a/yaserde/tests/deserializer.rs b/yaserde/tests/deserializer.rs
index fd06f20..21df4c0 100644
--- a/yaserde/tests/deserializer.rs
+++ b/yaserde/tests/deserializer.rs
@@ -1,8 +1,4 @@
 #[macro_use]
-extern crate log;
-extern crate xml;
-extern crate yaserde;
-#[macro_use]
 extern crate yaserde_derive;
 
 use std::io::Read;
diff --git a/yaserde/tests/errors.rs b/yaserde/tests/errors.rs
index ac68639..d91aa8f 100644
--- a/yaserde/tests/errors.rs
+++ b/yaserde/tests/errors.rs
@@ -1,8 +1,4 @@
 #[macro_use]
-extern crate log;
-extern crate xml;
-extern crate yaserde;
-#[macro_use]
 extern crate yaserde_derive;
 
 use std::io::Read;
diff --git a/yaserde/tests/ser_default.rs b/yaserde/tests/ser_default.rs
index 71c6225..b461a7e 100644
--- a/yaserde/tests/ser_default.rs
+++ b/yaserde/tests/ser_default.rs
@@ -1,6 +1,3 @@
-extern crate log;
-extern crate xml;
-extern crate yaserde;
 #[macro_use]
 extern crate yaserde_derive;
 
diff --git a/yaserde/tests/ser_namespace.rs b/yaserde/tests/ser_namespace.rs
index 0314d56..5af32e8 100644
--- a/yaserde/tests/ser_namespace.rs
+++ b/yaserde/tests/ser_namespace.rs
@@ -1,6 +1,3 @@
-extern crate log;
-extern crate xml;
-extern crate yaserde;
 #[macro_use]
 extern crate yaserde_derive;
 
@@ -182,6 +179,29 @@ fn ser_struct_default_namespace_via_attribute() {
   convert_and_validate!(model, content);
 }
 
+#[test]
+fn ser_struct_default_namespace_via_attribute_with_prefix() {
+  #[derive(YaSerialize, PartialEq, Debug)]
+  #[yaserde(
+    root = "tt",
+    prefix = "TTML",
+    default_namespace = "TTML",
+    namespace = "TTML: http://www.w3.org/ns/ttml",
+    namespace = "ttm: http://www.w3.org/ns/ttml#metadata"
+  )]
+  pub struct XmlStruct {
+    #[yaserde(prefix = "TTML")]
+    item: String,
+  }
+
+  let model = XmlStruct {
+    item: "something".to_string(),
+  };
+
+  let content = "<?xml version=\"1.0\" encoding=\"utf-8\"?><tt xmlns=\"http://www.w3.org/ns/ttml\" xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"><item>something</item></tt>";
+  convert_and_validate!(model, content);
+}
+
 #[test]
 fn ser_struct_namespace_nested() {
   #[derive(YaSerialize, Default, PartialEq, Debug)]
diff --git a/yaserde/tests/ser_option.rs b/yaserde/tests/ser_option.rs
index 5e34a6a..26f1c08 100644
--- a/yaserde/tests/ser_option.rs
+++ b/yaserde/tests/ser_option.rs
@@ -1,6 +1,3 @@
-extern crate log;
-extern crate xml;
-extern crate yaserde;
 #[macro_use]
 extern crate yaserde_derive;
 
diff --git a/yaserde/tests/ser_skip.rs b/yaserde/tests/ser_skip.rs
index fef63a8..53c6be0 100644
--- a/yaserde/tests/ser_skip.rs
+++ b/yaserde/tests/ser_skip.rs
@@ -1,6 +1,3 @@
-extern crate log;
-extern crate xml;
-extern crate yaserde;
 #[macro_use]
 extern crate yaserde_derive;
 
diff --git a/yaserde/tests/ser_type.rs b/yaserde/tests/ser_type.rs
index 3bf4934..1506cc2 100644
--- a/yaserde/tests/ser_type.rs
+++ b/yaserde/tests/ser_type.rs
@@ -1,6 +1,3 @@
-extern crate log;
-extern crate xml;
-extern crate yaserde;
 #[macro_use]
 extern crate yaserde_derive;
 
diff --git a/yaserde/tests/serializer.rs b/yaserde/tests/serializer.rs
index 3b73308..cd40425 100644
--- a/yaserde/tests/serializer.rs
+++ b/yaserde/tests/serializer.rs
@@ -1,6 +1,3 @@
-extern crate log;
-extern crate xml;
-extern crate yaserde;
 #[macro_use]
 extern crate yaserde_derive;
 
diff --git a/yaserde_derive/Cargo.toml b/yaserde_derive/Cargo.toml
index 0ce4b68..8b7ba13 100644
--- a/yaserde_derive/Cargo.toml
+++ b/yaserde_derive/Cargo.toml
@@ -9,6 +9,7 @@ repository = "https://github.com/media-io/yaserde"
 homepage = "https://github.com/media-io/yaserde"
 documentation = "https://docs.rs/yaserde"
 readme = "../README.md"
+edition = "2018"
 
 [dependencies]
 syn = { version = "~1.0", features = ["visit", "extra-traits"] }
diff --git a/yaserde_derive/src/de/expand_enum.rs b/yaserde_derive/src/de/expand_enum.rs
index 6748e5f..4fdb0ed 100644
--- a/yaserde_derive/src/de/expand_enum.rs
+++ b/yaserde_derive/src/de/expand_enum.rs
@@ -1,5 +1,5 @@
-use attribute::*;
-use field_type::*;
+use crate::attribute::*;
+use crate::field_type::*;
 use proc_macro2::TokenStream;
 use std::collections::BTreeMap;
 use syn::spanned::Spanned;
diff --git a/yaserde_derive/src/de/expand_struct.rs b/yaserde_derive/src/de/expand_struct.rs
index 6e9b66d..1f1d51e 100644
--- a/yaserde_derive/src/de/expand_struct.rs
+++ b/yaserde_derive/src/de/expand_struct.rs
@@ -1,6 +1,6 @@
-use attribute::*;
-use de::build_default_value::build_default_value;
-use field_type::*;
+use crate::attribute::*;
+use crate::de::build_default_value::build_default_value;
+use crate::field_type::*;
 use proc_macro2::{Span, TokenStream};
 use std::collections::BTreeMap;
 use syn::spanned::Spanned;
diff --git a/yaserde_derive/src/de/mod.rs b/yaserde_derive/src/de/mod.rs
index 455303b..4e3e8ab 100644
--- a/yaserde_derive/src/de/mod.rs
+++ b/yaserde_derive/src/de/mod.rs
@@ -2,7 +2,7 @@ pub mod build_default_value;
 pub mod expand_enum;
 pub mod expand_struct;
 
-use attribute;
+use crate::attribute;
 use proc_macro2::TokenStream;
 use syn;
 use syn::Ident;
diff --git a/yaserde_derive/src/ser/element.rs b/yaserde_derive/src/ser/element.rs
index 5a18601..313be33 100644
--- a/yaserde_derive/src/ser/element.rs
+++ b/yaserde_derive/src/ser/element.rs
@@ -1,4 +1,4 @@
-use attribute::*;
+use crate::attribute::*;
 use proc_macro2::{Ident, Span, TokenStream};
 
 pub fn enclose_formatted_characters(label: &Ident, label_name: String) -> TokenStream {
diff --git a/yaserde_derive/src/ser/expand_enum.rs b/yaserde_derive/src/ser/expand_enum.rs
index 32f50ed..f1902be 100644
--- a/yaserde_derive/src/ser/expand_enum.rs
+++ b/yaserde_derive/src/ser/expand_enum.rs
@@ -1,5 +1,5 @@
-use attribute::*;
-use field_type::*;
+use crate::attribute::*;
+use crate::field_type::*;
 use proc_macro2::TokenStream;
 use std::collections::BTreeMap;
 use syn::spanned::Spanned;
diff --git a/yaserde_derive/src/ser/expand_struct.rs b/yaserde_derive/src/ser/expand_struct.rs
index 3c94d4b..1411a03 100644
--- a/yaserde_derive/src/ser/expand_struct.rs
+++ b/yaserde_derive/src/ser/expand_struct.rs
@@ -1,5 +1,6 @@
-use attribute::*;
-use field_type::*;
+use crate::attribute::*;
+use crate::field_type::*;
+use crate::ser::element::*;
 use proc_macro2::TokenStream;
 use std::collections::BTreeMap;
 use std::string::ToString;
@@ -7,8 +8,6 @@ use syn::spanned::Spanned;
 use syn::DataStruct;
 use syn::Ident;
 
-use ser::element::*;
-
 pub fn serialize(
   data_struct: &DataStruct,
   name: &Ident,
@@ -27,7 +26,7 @@ pub fn serialize(
 
       let label = &field.ident;
 
-      let label_name = build_label_name(&field, &field_attrs);
+      let label_name = build_label_name(&field, &field_attrs, default_namespace);
 
       get_field_type(field).and_then(|f| match f {
         FieldType::FieldTypeString
@@ -240,7 +239,7 @@ pub fn serialize(
         ));
       }
 
-      let label_name = build_label_name(&field, &field_attrs);
+      let label_name = build_label_name(&field, &field_attrs, default_namespace);
       let conditions = condition_generator(label, &field_attrs);
 
       get_field_type(field).and_then(|f| match f {
@@ -411,16 +410,24 @@ pub fn serialize(
   }
 }
 
-fn build_label_name(field: &syn::Field, field_attrs: &YaSerdeAttribute) -> String {
-  format!(
-    "{}{}",
+fn build_label_name(
+  field: &syn::Field,
+  field_attrs: &YaSerdeAttribute,
+  default_namespace: &Option<String>,
+) -> String {
+  let prefix = if default_namespace == &field_attrs.prefix {
+    "".to_string()
+  } else {
     field_attrs
       .prefix
       .clone()
-      .map_or("".to_string(), |prefix| prefix + ":"),
-    field_attrs
-      .rename
-      .clone()
-      .unwrap_or_else(|| field.ident.as_ref().unwrap().to_string())
-  )
+      .map_or("".to_string(), |prefix| prefix + ":")
+  };
+
+  let label = field_attrs
+    .rename
+    .clone()
+    .unwrap_or_else(|| field.ident.as_ref().unwrap().to_string());
+
+  format!("{}{}", prefix, label)
 }
diff --git a/yaserde_derive/src/ser/mod.rs b/yaserde_derive/src/ser/mod.rs
index d801b61..68a1532 100644
--- a/yaserde_derive/src/ser/mod.rs
+++ b/yaserde_derive/src/ser/mod.rs
@@ -2,7 +2,7 @@ pub mod element;
 pub mod expand_enum;
 pub mod expand_struct;
 
-use attribute;
+use crate::attribute;
 use proc_macro2::TokenStream;
 use syn;
 use syn::Ident;
@@ -15,12 +15,16 @@ pub fn expand_derive_serialize(ast: &syn::DeriveInput) -> Result<TokenStream, St
   let root_attrs = attribute::YaSerdeAttribute::parse(attrs);
   let root = root_attrs.clone().root.unwrap_or_else(|| name.to_string());
 
-  let root = if let Some(prefix) = root_attrs.prefix {
-    prefix + ":" + &root
+  let prefix = if root_attrs.default_namespace == root_attrs.prefix {
+    "".to_string()
   } else {
-    root
+    root_attrs
+      .prefix
+      .map_or("".to_string(), |prefix| prefix + ":")
   };
 
+  let root = format!("{}{}", prefix, root);
+
   let impl_block = match *data {
     syn::Data::Struct(ref data_struct) => expand_struct::serialize(
       data_struct,