diff --git a/hy/compiler.py b/hy/compiler.py
index fac4cfa..51ab4fc 100644
--- a/hy/compiler.py
+++ b/hy/compiler.py
@@ -459,8 +459,9 @@ class HyASTCompiler(object):
                 try:
                     value = next(exprs_iter)
                 except StopIteration:
-                    msg = "Keyword argument {kw} needs a value"
-                    raise HyCompileError(msg.format(kw=str(expr)))
+                    raise HyTypeError(expr,
+                                      "Keyword argument {kw} needs "
+                                      "a value.".format(kw=str(expr[1:])))
 
                 compiled_value = self.compile(value)
                 ret += compiled_value
diff --git a/hy/lex/parser.py b/hy/lex/parser.py
index a63be3e..22aaf26 100644
--- a/hy/lex/parser.py
+++ b/hy/lex/parser.py
@@ -308,6 +308,9 @@ def t_identifier(p):
         if p.endswith("?") and p != "?":
             p = "is_%s" % (p[:-1])
 
+        if p.endswith("!") and p != "!":
+            p = "%s_bang" % (p[:-1])
+
         return p
 
     obj = ".".join([mangle(part) for part in obj.split(".")])
diff --git a/tests/compilers/test_ast.py b/tests/compilers/test_ast.py
index c68c609..768e724 100644
--- a/tests/compilers/test_ast.py
+++ b/tests/compilers/test_ast.py
@@ -439,6 +439,16 @@ def test_lambda_list_keywords_mixed():
                     "  (list x xs kwxs kwoxs))")
 
 
+def test_missing_keyword_argument_value():
+    """Ensure the compiler chokes on missing keyword argument values."""
+    try:
+        can_compile("((fn [x] x) :x)")
+    except HyTypeError as e:
+        assert(e.message == "Keyword argument :x needs a value.")
+    else:
+        assert(False)
+
+
 def test_ast_unicode_strings():
     """Ensure we handle unicode strings correctly"""
 
@@ -521,7 +531,16 @@ def test_cons_correct():
     can_compile("(cons a b)")
 
 
+
 def test_bad_setv():
     """Ensure setv handles error cases"""
     cant_compile("(setv if 1)")
     cant_compile("(setv (a b) [1 2])")
+
+
+def test_defn():
+    """Ensure that defn works correctly in various corner cases"""
+    cant_compile("(defn if [] 1)")
+    cant_compile("(defn \"hy\" [] 1)")
+    cant_compile("(defn :hy [] 1)")
+    can_compile("(defn &hy [] 1)")
diff --git a/tests/lex/test_lex.py b/tests/lex/test_lex.py
index cc95675..56ed52a 100644
--- a/tests/lex/test_lex.py
+++ b/tests/lex/test_lex.py
@@ -326,6 +326,24 @@ def test_lex_mangling_qmark():
     assert entry == [HySymbol(".is_foo.bar.is_baz")]
 
 
+def test_lex_mangling_bang():
+    """Ensure that identifiers ending with a bang get mangled ok"""
+    entry = tokenize("foo!")
+    assert entry == [HySymbol("foo_bang")]
+    entry = tokenize("!")
+    assert entry == [HySymbol("!")]
+    entry = tokenize("im!foo")
+    assert entry == [HySymbol("im!foo")]
+    entry = tokenize(".foo!")
+    assert entry == [HySymbol(".foo_bang")]
+    entry = tokenize("foo.bar!")
+    assert entry == [HySymbol("foo.bar_bang")]
+    entry = tokenize("foo!.bar")
+    assert entry == [HySymbol("foo_bang.bar")]
+    entry = tokenize(".foo!.bar.baz!")
+    assert entry == [HySymbol(".foo_bang.bar.baz_bang")]
+
+
 def test_simple_cons():
     """Check that cons gets tokenized correctly"""
     entry = tokenize("(a . b)")[0]
diff --git a/tests/native_tests/language.hy b/tests/native_tests/language.hy
index d468533..ec771e6 100644
--- a/tests/native_tests/language.hy
+++ b/tests/native_tests/language.hy
@@ -673,6 +673,12 @@
   (assert (= 43 (my-fun 42))))
 
 
+(defn test-defn-lambdakey []
+  "NATIVE: test defn with a &symbol function name"
+  (defn &hy [] 1)
+  (assert (= (&hy) 1)))
+
+
 (defn test-defn-do []
   "NATIVE: test defn evaluation order with do"
   (setv acc [])