diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index c2ac21c889..c19c15732d 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -405,10 +405,9 @@ Client JSON Protocol command exchange.
 The 'data' argument maps to the "arguments" dictionary passed in as
 part of a Client JSON Protocol command.  The 'data' member is optional
 and defaults to {} (an empty dictionary).  If present, it must be the
-string name of a complex type, a one-element array containing the name
-of a complex type, or a dictionary that declares an anonymous type
-with the same semantics as a 'struct' expression, with one exception
-noted below when 'gen' is used.
+string name of a complex type, or a dictionary that declares an
+anonymous type with the same semantics as a 'struct' expression, with
+one exception noted below when 'gen' is used.
 
 The 'returns' member describes what will appear in the "return" field
 of a Client JSON Protocol reply on successful completion of a command.
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 487998244b..bbeae4d322 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -499,7 +499,7 @@ def check_command(expr, expr_info):
 
     check_type(expr_info, "'data' for command '%s'" % name,
                expr.get('data'), allow_dict=True, allow_optional=True,
-               allow_metas=['union', 'struct'], allow_star=allow_star)
+               allow_metas=['struct'], allow_star=allow_star)
     returns_meta = ['union', 'struct']
     if name in returns_whitelist:
         returns_meta += ['built-in', 'alternate', 'enum']
@@ -517,7 +517,7 @@ def check_event(expr, expr_info):
     events.append(name)
     check_type(expr_info, "'data' for event '%s'" % name,
                expr.get('data'), allow_dict=True, allow_optional=True,
-               allow_metas=['union', 'struct'])
+               allow_metas=['struct'])
 
 def check_union(expr, expr_info):
     name = expr['union']
diff --git a/tests/qapi-schema/args-union.err b/tests/qapi-schema/args-union.err
index e69de29bb2..1d693d74da 100644
--- a/tests/qapi-schema/args-union.err
+++ b/tests/qapi-schema/args-union.err
@@ -0,0 +1 @@
+tests/qapi-schema/args-union.json:4: 'data' for command 'oops' cannot use union type 'Uni'
diff --git a/tests/qapi-schema/args-union.exit b/tests/qapi-schema/args-union.exit
index 573541ac97..d00491fd7e 100644
--- a/tests/qapi-schema/args-union.exit
+++ b/tests/qapi-schema/args-union.exit
@@ -1 +1 @@
-0
+1
diff --git a/tests/qapi-schema/args-union.json b/tests/qapi-schema/args-union.json
index db97ef643b..7bdcbb7f08 100644
--- a/tests/qapi-schema/args-union.json
+++ b/tests/qapi-schema/args-union.json
@@ -1,4 +1,4 @@
-# FIXME we should reject union arguments
+# we do not allow union arguments
 # TODO should we support this?
 { 'union': 'Uni', 'data': { 'case1': 'int', 'case2': 'str' } }
 { 'command': 'oops', 'data': 'Uni' }
diff --git a/tests/qapi-schema/args-union.out b/tests/qapi-schema/args-union.out
index 907080cce6..e69de29bb2 100644
--- a/tests/qapi-schema/args-union.out
+++ b/tests/qapi-schema/args-union.out
@@ -1,4 +0,0 @@
-[OrderedDict([('union', 'Uni'), ('data', OrderedDict([('case1', 'int'), ('case2', 'str')]))]),
- OrderedDict([('command', 'oops'), ('data', 'Uni')])]
-[{'enum_name': 'UniKind', 'enum_values': None}]
-[]