diff --git a/libpathod/language/actions.py b/libpathod/language/actions.py
index e86394a02..f5b828fe3 100644
--- a/libpathod/language/actions.py
+++ b/libpathod/language/actions.py
@@ -45,6 +45,8 @@ class _Action(base.Token):
 
 
 class PauseAt(_Action):
+    unique_name = None
+
     def __init__(self, offset, seconds):
         _Action.__init__(self, offset)
         self.seconds = seconds
@@ -93,6 +95,8 @@ class DisconnectAt(_Action):
 
 
 class InjectAt(_Action):
+    unique_name = None
+
     def __init__(self, offset, value):
         _Action.__init__(self, offset)
         self.value = value
diff --git a/libpathod/language/base.py b/libpathod/language/base.py
index 3773fde1a..2a9e4ed31 100644
--- a/libpathod/language/base.py
+++ b/libpathod/language/base.py
@@ -77,6 +77,15 @@ class Token(object):
         """
         return None
 
+    @property
+    def unique_name(self):
+        """
+            Controls uniqueness constraints for tokens. No two tokens with the
+            same name will be allowed. If no uniquness should be applied, this
+            should be None.
+        """
+        return self.__class__.__name__
+
     def resolve(self, settings, msg):
         """
             Resolves this token to ready it for transmission. This means that
diff --git a/libpathod/language/http.py b/libpathod/language/http.py
index 070cc5f44..daee7e54a 100644
--- a/libpathod/language/http.py
+++ b/libpathod/language/http.py
@@ -46,6 +46,8 @@ class Method(base.OptionsOrValue):
 
 
 class _HeaderMixin(object):
+    unique_name = None
+
     def format_header(self, key, value):
         return [key, ": ", value, "\r\n"]
 
@@ -166,6 +168,7 @@ class _HTTPMessage(message.Message):
 
 
 class Response(_HTTPMessage):
+    unique_name = None
     comps = (
         Body,
         Header,
diff --git a/libpathod/language/message.py b/libpathod/language/message.py
index b5ef70455..dbc0cfddf 100644
--- a/libpathod/language/message.py
+++ b/libpathod/language/message.py
@@ -1,5 +1,5 @@
 import abc
-from . import actions
+from . import actions, exceptions
 
 LOG_TRUNCATE = 1024
 
@@ -9,6 +9,17 @@ class Message(object):
     logattrs = []
 
     def __init__(self, tokens):
+        track = set([])
+        for i in tokens:
+            if i.unique_name:
+                if i.unique_name in track:
+                    raise exceptions.ParseException(
+                        "Message has multiple %s clauses, "
+                        "but should only have one." % i.unique_name,
+                        0, 0
+                    )
+                else:
+                    track.add(i.unique_name)
         self.tokens = tokens
 
     def toks(self, klass):
diff --git a/test/test_language_actions.py b/test/test_language_actions.py
index 7676fb726..b7361dfff 100644
--- a/test/test_language_actions.py
+++ b/test/test_language_actions.py
@@ -8,6 +8,11 @@ def parse_request(s):
     return language.parse_requests(s)[0]
 
 
+def test_unique_name():
+    assert not actions.PauseAt(0, "f").unique_name
+    assert actions.DisconnectAt(0).unique_name
+
+
 class TestDisconnects:
     def test_parse_response(self):
         a = language.parse_response("400:d0").actions[0]
diff --git a/test/test_language_base.py b/test/test_language_base.py
index bd67c0109..404b302d4 100644
--- a/test/test_language_base.py
+++ b/test/test_language_base.py
@@ -310,6 +310,11 @@ class TBoolean(base.Boolean):
     name = "test"
 
 
+def test_unique_name():
+    b = TBoolean(True)
+    assert b.unique_name
+
+
 class test_boolean():
     e = TBoolean.expr()
     assert e.parseString("test")[0].value
diff --git a/test/test_language_http.py b/test/test_language_http.py
index a7313bfb9..17bce802e 100644
--- a/test/test_language_http.py
+++ b/test/test_language_http.py
@@ -342,3 +342,11 @@ def test_pathodspec_freeze():
     )
     assert e.freeze({})
     assert e.values({})
+
+
+def test_unique_components():
+    tutils.raises(
+        "multiple body clauses",
+        language.parse_response,
+        "400:b@1:b@1"
+    )