diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index c68659a7b1..833768ef0e 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -17,19 +17,12 @@
 
 
 def gen_command_decl(name, arg_type, ret_type):
-    argstr = ''
-    if arg_type:
-        for memb in arg_type.members:
-            if memb.optional:
-                argstr += 'bool has_%s, ' % c_name(memb.name)
-            argstr += '%s %s, ' % (memb.type.c_type(is_param=True),
-                                   c_name(memb.name))
     return mcgen('''
-%(c_type)s qmp_%(c_name)s(%(args)sError **errp);
+%(c_type)s qmp_%(c_name)s(%(params)s);
 ''',
                  c_type=(ret_type and ret_type.c_type()) or 'void',
                  c_name=c_name(name),
-                 args=argstr)
+                 params=gen_params(arg_type, 'Error **errp'))
 
 
 def gen_err_check(err):
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 5873a05888..d15fad98f3 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -15,21 +15,9 @@
 
 
 def gen_event_send_proto(name, arg_type):
-    api_name = "void qapi_event_send_%s(" % c_name(name).lower()
-    l = len(api_name)
-
-    if arg_type:
-        for m in arg_type.members:
-            if m.optional:
-                api_name += "bool has_%s,\n" % c_name(m.name)
-                api_name += "".ljust(l)
-
-            api_name += "%s %s,\n" % (m.type.c_type(is_param=True),
-                                      c_name(m.name))
-            api_name += "".ljust(l)
-
-    api_name += "Error **errp)"
-    return api_name
+    return 'void qapi_event_send_%(c_name)s(%(param)s)' % {
+        'c_name': c_name(name.lower()),
+        'param': gen_params(arg_type, 'Error **errp')}
 
 
 def gen_event_send_decl(name, arg_type):
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 7ac72f6a78..6b6f1aecdc 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1469,6 +1469,22 @@ def gen_enum(name, values, prefix=None):
                  c_name=c_name(name))
     return ret
 
+def gen_params(arg_type, extra):
+    if not arg_type:
+        return extra
+    assert not arg_type.variants
+    ret = ''
+    sep = ''
+    for memb in arg_type.members:
+        ret += sep
+        sep = ', '
+        if memb.optional:
+            ret += 'bool has_%s, ' % c_name(memb.name)
+        ret += '%s %s' % (memb.type.c_type(is_param=True), c_name(memb.name))
+    if extra:
+        ret += sep + extra
+    return ret
+
 #
 # Common command line parsing
 #