diff --git a/src/attention.rs b/src/attention.rs
index 398b2bf..4bfffd7 100644
--- a/src/attention.rs
+++ b/src/attention.rs
@@ -20,6 +20,11 @@ mod tests {
     use minidom::Element;
     use error::Error;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Attention, 0);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<attention xmlns='urn:xmpp:attention:0'/>".parse().unwrap();
diff --git a/src/bind.rs b/src/bind.rs
index 1922093..6bfa8a3 100644
--- a/src/bind.rs
+++ b/src/bind.rs
@@ -98,6 +98,11 @@ impl From<Bind> for Element {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Bind, 80);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>".parse().unwrap();
diff --git a/src/blocking.rs b/src/blocking.rs
index 6b6894c..87a2fbd 100644
--- a/src/blocking.rs
+++ b/src/blocking.rs
@@ -98,6 +98,14 @@ generate_empty_element!(
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_size() {
+        assert_size!(BlocklistRequest, 0);
+        assert_size!(BlocklistResult, 24);
+        assert_size!(Block, 24);
+        assert_size!(Unblock, 24);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<blocklist xmlns='urn:xmpp:blocking'/>".parse().unwrap();
diff --git a/src/bookmarks.rs b/src/bookmarks.rs
index 11b4a42..8ae0639 100644
--- a/src/bookmarks.rs
+++ b/src/bookmarks.rs
@@ -74,6 +74,13 @@ mod tests {
     use minidom::Element;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Conference, 152);
+        assert_size!(Url, 48);
+        assert_size!(Storage, 48);
+    }
+
     #[test]
     fn empty() {
         let elem: Element = "<storage xmlns='storage:bookmarks'/>".parse().unwrap();
diff --git a/src/caps.rs b/src/caps.rs
index 25c851f..7fcaea8 100644
--- a/src/caps.rs
+++ b/src/caps.rs
@@ -211,6 +211,11 @@ mod tests {
     use caps;
     use base64;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Caps, 104);
+    }
+
     #[test]
     fn test_parse() {
         let elem: Element = "<c xmlns='http://jabber.org/protocol/caps' hash='sha-256' node='coucou' ver='K1Njy3HZBThlo4moOD5gBGhn0U0oK7/CbfLlIUDi6o4='/>".parse().unwrap();
diff --git a/src/chatstates.rs b/src/chatstates.rs
index c9fabd5..477bdde 100644
--- a/src/chatstates.rs
+++ b/src/chatstates.rs
@@ -37,6 +37,11 @@ mod tests {
     use error::Error;
     use ns;
 
+    #[test]
+    fn test_size() {
+        assert_size!(ChatState, 1);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<active xmlns='http://jabber.org/protocol/chatstates'/>".parse().unwrap();
diff --git a/src/component.rs b/src/component.rs
index 27229f2..503e103 100644
--- a/src/component.rs
+++ b/src/component.rs
@@ -47,6 +47,11 @@ mod tests {
     use try_from::TryFrom;
     use minidom::Element;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Handshake, 24);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<handshake xmlns='jabber:component:accept'/>".parse().unwrap();
diff --git a/src/data_forms.rs b/src/data_forms.rs
index a439779..3fccd72 100644
--- a/src/data_forms.rs
+++ b/src/data_forms.rs
@@ -268,6 +268,15 @@ impl From<DataForm> for Element {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Option_, 48);
+        assert_size!(FieldType, 1);
+        assert_size!(Field, 128);
+        assert_size!(DataFormType, 1);
+        assert_size!(DataForm, 104);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<x xmlns='jabber:x:data' type='result'/>".parse().unwrap();
diff --git a/src/date.rs b/src/date.rs
index a344eb5..5f2038d 100644
--- a/src/date.rs
+++ b/src/date.rs
@@ -43,6 +43,11 @@ mod tests {
     use chrono::{Datelike, Timelike};
     use std::error::Error as StdError;
 
+    #[test]
+    fn test_size() {
+        assert_size!(DateTime, 16);
+    }
+
     #[test]
     fn test_simple() {
         let date: DateTime = "2002-09-10T23:08:25Z".parse().unwrap();
diff --git a/src/delay.rs b/src/delay.rs
index 581e72e..c4f7518 100644
--- a/src/delay.rs
+++ b/src/delay.rs
@@ -39,6 +39,11 @@ mod tests {
     use error::Error;
     use std::str::FromStr;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Delay, 112);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<delay xmlns='urn:xmpp:delay' from='capulet.com' stamp='2002-09-10T23:08:25Z'/>".parse().unwrap();
diff --git a/src/disco.rs b/src/disco.rs
index 59166eb..7b43553 100644
--- a/src/disco.rs
+++ b/src/disco.rs
@@ -235,6 +235,18 @@ mod tests {
     use compare_elements::NamespaceAwareCompare;
     use std::str::FromStr;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Identity, 96);
+        assert_size!(Feature, 24);
+        assert_size!(DiscoInfoQuery, 24);
+        assert_size!(DiscoInfoResult, 96);
+
+        assert_size!(Item, 120);
+        assert_size!(DiscoItemsQuery, 24);
+        assert_size!(DiscoItemsResult, 48);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity category='client' type='pc'/><feature var='http://jabber.org/protocol/disco#info'/></query>".parse().unwrap();
diff --git a/src/ecaps2.rs b/src/ecaps2.rs
index 6e71040..d4811b5 100644
--- a/src/ecaps2.rs
+++ b/src/ecaps2.rs
@@ -152,6 +152,11 @@ mod tests {
     use minidom::Element;
     use error::Error;
 
+    #[test]
+    fn test_size() {
+        assert_size!(ECaps2, 24);
+    }
+
     #[test]
     fn test_parse() {
         let elem: Element = "<c xmlns='urn:xmpp:caps'><hash xmlns='urn:xmpp:hashes:2' algo='sha-256'>K1Njy3HZBThlo4moOD5gBGhn0U0oK7/CbfLlIUDi6o4=</hash><hash xmlns='urn:xmpp:hashes:2' algo='sha3-256'>+sDTQqBmX6iG/X3zjt06fjZMBBqL/723knFIyRf0sg8=</hash></c>".parse().unwrap();
diff --git a/src/eme.rs b/src/eme.rs
index 51eb2a6..271b842 100644
--- a/src/eme.rs
+++ b/src/eme.rs
@@ -28,6 +28,11 @@ mod tests {
     use minidom::Element;
     use error::Error;
 
+    #[test]
+    fn test_size() {
+        assert_size!(ExplicitMessageEncryption, 48);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<encryption xmlns='urn:xmpp:eme:0' namespace='urn:xmpp:otr:0'/>".parse().unwrap();
diff --git a/src/forwarding.rs b/src/forwarding.rs
index b65b450..fbfacb1 100644
--- a/src/forwarding.rs
+++ b/src/forwarding.rs
@@ -30,6 +30,11 @@ mod tests {
     use minidom::Element;
     use error::Error;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Forwarded, 392);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<forwarded xmlns='urn:xmpp:forward:0'/>".parse().unwrap();
diff --git a/src/hashes.rs b/src/hashes.rs
index bf7fafb..7063dbc 100644
--- a/src/hashes.rs
+++ b/src/hashes.rs
@@ -133,6 +133,12 @@ mod tests {
     use try_from::TryFrom;
     use minidom::Element;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Algo, 32);
+        assert_size!(Hash, 56);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<hash xmlns='urn:xmpp:hashes:2' algo='sha-256'>2XarmwTlNxDAMkvymloX3S5+VbylNrJt/l5QyPa+YoU=</hash>".parse().unwrap();
diff --git a/src/ibb.rs b/src/ibb.rs
index bede2f0..e595fe4 100644
--- a/src/ibb.rs
+++ b/src/ibb.rs
@@ -76,6 +76,14 @@ mod tests {
     use error::Error;
     use std::error::Error as StdError;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Stanza, 1);
+        assert_size!(Open, 32);
+        assert_size!(Data, 56);
+        assert_size!(Close, 24);
+    }
+
     #[test]
     fn test_simple() {
         let sid = StreamId(String::from("coucou"));
diff --git a/src/ibr.rs b/src/ibr.rs
index 72324de..71256b6 100644
--- a/src/ibr.rs
+++ b/src/ibr.rs
@@ -96,6 +96,11 @@ mod tests {
     use super::*;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Query, 152);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<query xmlns='jabber:iq:register'/>".parse().unwrap();
diff --git a/src/idle.rs b/src/idle.rs
index 2704654..45352a2 100644
--- a/src/idle.rs
+++ b/src/idle.rs
@@ -27,6 +27,11 @@ mod tests {
     use std::str::FromStr;
     use std::error::Error as StdError;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Idle, 16);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<idle xmlns='urn:xmpp:idle:1' since='2017-05-21T20:19:55+01:00'/>".parse().unwrap();
diff --git a/src/iq.rs b/src/iq.rs
index aeeb836..b5f27bf 100644
--- a/src/iq.rs
+++ b/src/iq.rs
@@ -226,6 +226,12 @@ mod tests {
     use compare_elements::NamespaceAwareCompare;
     use disco::DiscoInfoQuery;
 
+    #[test]
+    fn test_size() {
+        assert_size!(IqType, 216);
+        assert_size!(Iq, 384);
+    }
+
     #[test]
     fn test_require_type() {
         #[cfg(not(feature = "component"))]
diff --git a/src/jingle.rs b/src/jingle.rs
index 3102b10..38577f8 100644
--- a/src/jingle.rs
+++ b/src/jingle.rs
@@ -533,6 +533,20 @@ impl From<Jingle> for Element {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Action, 1);
+        assert_size!(Creator, 1);
+        assert_size!(Senders, 1);
+        assert_size!(Disposition, 1);
+        assert_size!(ContentId, 24);
+        assert_size!(Content, 344);
+        assert_size!(Reason, 1);
+        assert_size!(ReasonElement, 32);
+        assert_size!(SessionId, 24);
+        assert_size!(Jingle, 256);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<jingle xmlns='urn:xmpp:jingle:1' action='session-initiate' sid='coucou'/>".parse().unwrap();
diff --git a/src/jingle_ft.rs b/src/jingle_ft.rs
index e206ab3..0a3c022 100644
--- a/src/jingle_ft.rs
+++ b/src/jingle_ft.rs
@@ -348,6 +348,15 @@ mod tests {
     use hashes::Algo;
     use base64;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Range, 48);
+        assert_size!(File, 184);
+        assert_size!(Description, 184);
+        assert_size!(Checksum, 216);
+        assert_size!(Received, 32);
+    }
+
     #[test]
     fn test_description() {
         let elem: Element = r#"
diff --git a/src/jingle_ibb.rs b/src/jingle_ibb.rs
index 7438133..c56c73d 100644
--- a/src/jingle_ibb.rs
+++ b/src/jingle_ibb.rs
@@ -29,6 +29,11 @@ mod tests {
     use error::Error;
     use std::error::Error as StdError;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Transport, 32);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<transport xmlns='urn:xmpp:jingle:transports:ibb:1' block-size='3' sid='coucou'/>".parse().unwrap();
diff --git a/src/jingle_message.rs b/src/jingle_message.rs
index d8e3038..150e7a0 100644
--- a/src/jingle_message.rs
+++ b/src/jingle_message.rs
@@ -121,6 +121,11 @@ impl From<JingleMI> for Element {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_size() {
+        assert_size!(JingleMI, 136);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<accept xmlns='urn:xmpp:jingle-message:0' id='coucou'/>".parse().unwrap();
diff --git a/src/jingle_s5b.rs b/src/jingle_s5b.rs
index f6f05be..a5fdff0 100644
--- a/src/jingle_s5b.rs
+++ b/src/jingle_s5b.rs
@@ -277,6 +277,17 @@ mod tests {
     use std::str::FromStr;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Type, 1);
+        assert_size!(Mode, 1);
+        assert_size!(CandidateId, 24);
+        assert_size!(StreamId, 24);
+        assert_size!(Candidate, 128);
+        assert_size!(TransportPayload, 32);
+        assert_size!(Transport, 88);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<transport xmlns='urn:xmpp:jingle:transports:s5b:1' sid='coucou'/>".parse().unwrap();
diff --git a/src/macros.rs b/src/macros.rs
index 5793fef..3deade1 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -510,3 +510,9 @@ macro_rules! generate_element {
         }
     );
 }
+
+macro_rules! assert_size (
+    ($t:ty, $sz:expr) => (
+        assert_eq!(::std::mem::size_of::<$t>(), $sz);
+    );
+);
diff --git a/src/mam.rs b/src/mam.rs
index 11850a2..4456412 100644
--- a/src/mam.rs
+++ b/src/mam.rs
@@ -191,6 +191,17 @@ mod tests {
     use super::*;
     use std::str::FromStr;
 
+    #[test]
+    fn test_size() {
+        assert_size!(QueryId, 24);
+        assert_size!(Query, 232);
+        assert_size!(Result_, 440);
+        assert_size!(Complete, 1);
+        assert_size!(Fin, 88);
+        assert_size!(DefaultPrefs, 1);
+        assert_size!(Prefs, 56);
+    }
+
     #[test]
     fn test_query() {
         let elem: Element = "<query xmlns='urn:xmpp:mam:2'/>".parse().unwrap();
diff --git a/src/media_element.rs b/src/media_element.rs
index 7ad264b..722780f 100644
--- a/src/media_element.rs
+++ b/src/media_element.rs
@@ -51,6 +51,12 @@ mod tests {
     use data_forms::DataForm;
     use std::error::Error as StdError;
 
+    #[test]
+    fn test_size() {
+        assert_size!(URI, 48);
+        assert_size!(MediaElement, 56);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<media xmlns='urn:xmpp:media-element'/>".parse().unwrap();
diff --git a/src/message.rs b/src/message.rs
index 7506a3f..2e9d9c6 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -234,6 +234,15 @@ mod tests {
     use std::str::FromStr;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(MessageType, 1);
+        assert_size!(Body, 24);
+        assert_size!(Subject, 24);
+        assert_size!(Thread, 24);
+        assert_size!(Message, 272);
+    }
+
     #[test]
     fn test_simple() {
         #[cfg(not(feature = "component"))]
diff --git a/src/message_correct.rs b/src/message_correct.rs
index 0483451..e8233ee 100644
--- a/src/message_correct.rs
+++ b/src/message_correct.rs
@@ -25,6 +25,11 @@ mod tests {
     use minidom::Element;
     use error::Error;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Replace, 24);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<replace xmlns='urn:xmpp:message-correct:0' id='coucou'/>".parse().unwrap();
diff --git a/src/mood.rs b/src/mood.rs
index 8612a42..6bf8bd2 100644
--- a/src/mood.rs
+++ b/src/mood.rs
@@ -272,6 +272,12 @@ mod tests {
     use try_from::TryFrom;
     use minidom::Element;
 
+    #[test]
+    fn test_size() {
+        assert_size!(MoodEnum, 1);
+        assert_size!(Text, 24);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<happy xmlns='http://jabber.org/protocol/mood'/>".parse().unwrap();
diff --git a/src/nick.rs b/src/nick.rs
index 9844e93..2d2f90c 100644
--- a/src/nick.rs
+++ b/src/nick.rs
@@ -16,6 +16,11 @@ mod tests {
     use minidom::Element;
     use error::Error;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Nick, 24);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<nick xmlns='http://jabber.org/protocol/nick'>Link Mauve</nick>".parse().unwrap();
diff --git a/src/ping.rs b/src/ping.rs
index 0af81c0..557f535 100644
--- a/src/ping.rs
+++ b/src/ping.rs
@@ -22,6 +22,11 @@ mod tests {
     use minidom::Element;
     use error::Error;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Ping, 0);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<ping xmlns='urn:xmpp:ping'/>".parse().unwrap();
diff --git a/src/presence.rs b/src/presence.rs
index 8bde178..02a9a9c 100644
--- a/src/presence.rs
+++ b/src/presence.rs
@@ -323,6 +323,13 @@ mod tests {
     use super::*;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Show, 1);
+        assert_size!(Type, 1);
+        assert_size!(Presence, 224);
+    }
+
     #[test]
     fn test_simple() {
         #[cfg(not(feature = "component"))]
diff --git a/src/receipts.rs b/src/receipts.rs
index 898a5dd..ecf0a21 100644
--- a/src/receipts.rs
+++ b/src/receipts.rs
@@ -33,6 +33,12 @@ mod tests {
     use minidom::Element;
     use ns;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Request, 0);
+        assert_size!(Received, 24);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<request xmlns='urn:xmpp:receipts'/>".parse().unwrap();
diff --git a/src/roster.rs b/src/roster.rs
index 0bb7439..eeebddf 100644
--- a/src/roster.rs
+++ b/src/roster.rs
@@ -85,6 +85,14 @@ mod tests {
     use std::str::FromStr;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Group, 24);
+        assert_size!(Subscription, 1);
+        assert_size!(Item, 128);
+        assert_size!(Roster, 48);
+    }
+
     #[test]
     fn test_get() {
         let elem: Element = "<query xmlns='jabber:iq:roster'/>".parse().unwrap();
diff --git a/src/rsm.rs b/src/rsm.rs
index d16751a..2f17693 100644
--- a/src/rsm.rs
+++ b/src/rsm.rs
@@ -158,6 +158,12 @@ mod tests {
     use super::*;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(SetQuery, 80);
+        assert_size!(SetResult, 80);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<set xmlns='http://jabber.org/protocol/rsm'/>".parse().unwrap();
diff --git a/src/sasl.rs b/src/sasl.rs
index f27167b..5272fd0 100644
--- a/src/sasl.rs
+++ b/src/sasl.rs
@@ -215,6 +215,18 @@ mod tests {
     use try_from::TryFrom;
     use minidom::Element;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Mechanism, 1);
+        assert_size!(Auth, 32);
+        assert_size!(Challenge, 24);
+        assert_size!(Response, 24);
+        assert_size!(Abort, 0);
+        assert_size!(Success, 24);
+        assert_size!(DefinedCondition, 1);
+        assert_size!(Failure, 32);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' mechanism='PLAIN'/>".parse().unwrap();
diff --git a/src/sm.rs b/src/sm.rs
index e93aa24..dfc3dff 100644
--- a/src/sm.rs
+++ b/src/sm.rs
@@ -144,6 +144,20 @@ mod tests {
     use try_from::TryFrom;
     use minidom::Element;
 
+    #[test]
+    fn test_size() {
+        assert_size!(A, 4);
+        assert_size!(ResumeAttr, 1);
+        assert_size!(Enable, 12);
+        assert_size!(StreamId, 24);
+        assert_size!(Enabled, 64);
+        assert_size!(Failed, 12);
+        assert_size!(R, 0);
+        assert_size!(Resume, 32);
+        assert_size!(Resumed, 32);
+        assert_size!(StreamManagement, 0);
+    }
+
     #[test]
     fn a() {
         let elem: Element = "<a xmlns='urn:xmpp:sm:3' h='5'".parse().unwrap();
diff --git a/src/stanza_error.rs b/src/stanza_error.rs
index 37e71be..480b1d8 100644
--- a/src/stanza_error.rs
+++ b/src/stanza_error.rs
@@ -289,6 +289,13 @@ impl From<StanzaError> for Element {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_size() {
+        assert_size!(ErrorType, 1);
+        assert_size!(DefinedCondition, 1);
+        assert_size!(StanzaError, 208);
+    }
+
     #[test]
     fn test_simple() {
         #[cfg(not(feature = "component"))]
diff --git a/src/stanza_id.rs b/src/stanza_id.rs
index 07e947a..9dc3698 100644
--- a/src/stanza_id.rs
+++ b/src/stanza_id.rs
@@ -42,6 +42,12 @@ mod tests {
     use error::Error;
     use std::str::FromStr;
 
+    #[test]
+    fn test_size() {
+        assert_size!(StanzaId, 96);
+        assert_size!(OriginId, 24);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<stanza-id xmlns='urn:xmpp:sid:0' id='coucou' by='coucou@coucou'/>".parse().unwrap();
diff --git a/src/stream.rs b/src/stream.rs
index 693796d..b81ba77 100644
--- a/src/stream.rs
+++ b/src/stream.rs
@@ -76,6 +76,11 @@ mod tests {
     use try_from::TryFrom;
     use minidom::Element;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Stream, 216);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<stream:stream xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams' xml:lang='en' version='1.0' id='abc' from='some-server.example'/>".parse().unwrap();
diff --git a/src/version.rs b/src/version.rs
index 4354df5..7ed8974 100644
--- a/src/version.rs
+++ b/src/version.rs
@@ -43,6 +43,12 @@ mod tests {
     use minidom::Element;
     use compare_elements::NamespaceAwareCompare;
 
+    #[test]
+    fn test_size() {
+        assert_size!(VersionQuery, 0);
+        assert_size!(VersionResult, 72);
+    }
+
     #[test]
     fn simple() {
         let elem: Element = "<query xmlns='jabber:iq:version'><name>xmpp-rs</name><version>0.3.0</version></query>".parse().unwrap();
diff --git a/src/websocket.rs b/src/websocket.rs
index 102690c..2f87437 100644
--- a/src/websocket.rs
+++ b/src/websocket.rs
@@ -75,6 +75,11 @@ mod tests {
     use try_from::TryFrom;
     use minidom::Element;
 
+    #[test]
+    fn test_size() {
+        assert_size!(Open, 216);
+    }
+
     #[test]
     fn test_simple() {
         let elem: Element = "<open xmlns='urn:ietf:params:xml:ns:xmpp-framing'/>".parse().unwrap();