diff --git a/Cargo.toml b/Cargo.toml
index d8b0826..700d7f1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ categories = ["parsing", "network-programming"]
 license = "MPL-2.0"
 
 [dependencies]
-minidom = "0.4.1"
+minidom = "0.4.3"
 jid = "0.2.0"
 base64 = "0.5.0"
 digest = "0.5.0"
diff --git a/src/ibb.rs b/src/ibb.rs
index 71bf695..18cb14e 100644
--- a/src/ibb.rs
+++ b/src/ibb.rs
@@ -113,7 +113,7 @@ impl Into<Element> for IBB {
             IBB::Open { block_size, sid, stanza } => {
                 Element::builder("open")
                         .ns(ns::IBB)
-                        .attr("block-size", format!("{}", block_size))
+                        .attr("block-size", block_size)
                         .attr("sid", sid)
                         .attr("stanza", stanza)
                         .build()
@@ -121,7 +121,7 @@ impl Into<Element> for IBB {
             IBB::Data { seq, sid, data } => {
                 Element::builder("data")
                         .ns(ns::IBB)
-                        .attr("seq", format!("{}", seq))
+                        .attr("seq", seq)
                         .attr("sid", sid)
                         .append(base64::encode(&data))
                         .build()
diff --git a/src/jingle_ft.rs b/src/jingle_ft.rs
index 1a4550c..1d37b6a 100644
--- a/src/jingle_ft.rs
+++ b/src/jingle_ft.rs
@@ -24,11 +24,8 @@ impl IntoElements for Range {
     fn into_elements(self, emitter: &mut ElementEmitter) {
         let mut elem = Element::builder("range")
                                .ns(ns::JINGLE_FT)
-                               .attr("offset", format!("{}", self.offset))
-                               .attr("length", match self.length {
-                                    Some(length) => Some(format!("{}", length)),
-                                    None => None
-                                })
+                               .attr("offset", self.offset)
+                               .attr("length", self.length)
                                .build();
         for hash in self.hashes {
             elem.append_child(hash.into());
diff --git a/src/jingle_ibb.rs b/src/jingle_ibb.rs
index 6f789d3..afbf11c 100644
--- a/src/jingle_ibb.rs
+++ b/src/jingle_ibb.rs
@@ -43,7 +43,7 @@ impl Into<Element> for Transport {
     fn into(self) -> Element {
         Element::builder("transport")
                 .ns(ns::JINGLE_IBB)
-                .attr("block-size", format!("{}", self.block_size))
+                .attr("block-size", self.block_size)
                 .attr("sid", self.sid)
                 .attr("stanza", self.stanza)
                 .build()
diff --git a/src/jingle_s5b.rs b/src/jingle_s5b.rs
index 42c188f..316a321 100644
--- a/src/jingle_s5b.rs
+++ b/src/jingle_s5b.rs
@@ -70,8 +70,8 @@ impl Into<Element> for Candidate {
                 .attr("cid", self.cid)
                 .attr("host", self.host)
                 .attr("jid", self.jid)
-                .attr("port", match self.port { Some(port) => Some(format!("{}", port)), None => None })
-                .attr("priority", format!("{}", self.priority))
+                .attr("port", self.port)
+                .attr("priority", self.priority)
                 .attr("type", self.type_)
                 .build()
     }
diff --git a/src/rsm.rs b/src/rsm.rs
index 21d86ee..e8d7109 100644
--- a/src/rsm.rs
+++ b/src/rsm.rs
@@ -103,7 +103,7 @@ impl Into<Element> for Set {
         if self.first.is_some() {
             elem.append_child(Element::builder("first")
                                       .ns(ns::RSM)
-                                      .attr("index", self.first_index.map(|index| format!("{}", index)))
+                                      .attr("index", self.first_index)
                                       .append(self.first).build());
         }
         if self.index.is_some() {