diff --git a/scripts/qapi.py b/scripts/qapi.py
index 853f9a3..281e762 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -429,6 +429,18 @@ def check_type(expr_info, source, value, allow_array = False,
                    allow_metas=['built-in', 'union', 'alternate', 'struct',
                                 'enum'])

+def check_member_clash(expr_info, base_name, data, source = ""):
+    base = find_struct(base_name)
+    assert base
+    base_members = base['data']
+    for key in data.keys():
+        if key in base_members:
+            raise QAPIExprError(expr_info,
+                                "Member name '%s'%s clashes with base '%s'"
+                                %(key, source, base_name))
+    if base.get('base'):
+        check_member_clash(expr_info, base['base'], data, source)
+
 def check_command(expr, expr_info):
     name = expr['command']
     allow_star = expr.has_key('gen')
@@ -518,9 +530,14 @@ def check_union(expr, expr_info):
         check_name(expr_info, "Member of union '%s'" % name, key)

         # Each value must name a known type; futhermore, in flat unions,
-        # branches must be a struct
+        # branches must be a struct with no overlapping member names
         check_type(expr_info, "Member '%s' of union '%s'" % (key, name),
                    value, allow_array=True, allow_metas=allow_metas)
+        if base:
+            branch_struct = find_struct(value)
+            assert branch_struct
+            check_member_clash(expr_info, expr['base'], branch_struct['data'],
+                               " of branch '%s'" %key)

         # If the discriminator names an enum type, then all members
         # of 'data' must also be members of the enum type.
@@ -597,6 +614,8 @@ def check_struct(expr, expr_info):
                allow_dict=True, allow_optional=True)
     check_type(expr_info, "'base' for type '%s'" % name, expr.get('base'),
                allow_metas=['struct'])
+    if expr.get('base'):
+        check_member_clash(expr_info, expr['base'], expr['data'])

 def check_exprs(schema):
     for expr_elem in schema.exprs:
diff --git a/tests/Makefile b/tests/Makefile
index 0cd114f..eb5655e 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -242,7 +242,8 @@ check-qapi-schema-y := $(addprefix tests/qapi-schema/, \
 	include-simple.json include-relpath.json include-format-err.json \
 	include-non-file.json include-no-file.json include-before-err.json \
 	include-nested-err.json include-self-cycle.json include-cycle.json \
-	include-repetition.json event-nest-struct.json event-case.json)
+	include-repetition.json event-nest-struct.json event-case.json \
+	struct-base-clash.json struct-base-clash-deep.json )

 GENERATED_HEADERS += tests/test-qapi-types.h tests/test-qapi-visit.h \
 		     tests/test-qmp-commands.h tests/test-qapi-event.h
diff --git a/tests/qapi-schema/flat-union-branch-clash.err b/tests/qapi-schema/flat-union-branch-clash.err
index e69de29..f112766 100644
--- a/tests/qapi-schema/flat-union-branch-clash.err
+++ b/tests/qapi-schema/flat-union-branch-clash.err
@@ -0,0 +1 @@
+tests/qapi-schema/flat-union-branch-clash.json:10: Member name 'name' of branch 'value1' clashes with base 'Base'
diff --git a/tests/qapi-schema/flat-union-branch-clash.exit b/tests/qapi-schema/flat-union-branch-clash.exit
index 573541a..d00491f 100644
--- a/tests/qapi-schema/flat-union-branch-clash.exit
+++ b/tests/qapi-schema/flat-union-branch-clash.exit
@@ -1 +1 @@
-0
+1
diff --git a/tests/qapi-schema/flat-union-branch-clash.json b/tests/qapi-schema/flat-union-branch-clash.json
index 8b0b807..b3c6ffe 100644
--- a/tests/qapi-schema/flat-union-branch-clash.json
+++ b/tests/qapi-schema/flat-union-branch-clash.json
@@ -1,4 +1,4 @@
-# FIXME: we should check for no duplicate keys between branches and base
+# we check for no duplicate keys between branches and base
 { 'enum': 'TestEnum',
   'data': [ 'value1', 'value2' ] }
 { 'struct': 'Base',
diff --git a/tests/qapi-schema/flat-union-branch-clash.out b/tests/qapi-schema/flat-union-branch-clash.out
index 04c2395..e69de29 100644
--- a/tests/qapi-schema/flat-union-branch-clash.out
+++ b/tests/qapi-schema/flat-union-branch-clash.out
@@ -1,9 +0,0 @@
-[OrderedDict([('enum', 'TestEnum'), ('data', ['value1', 'value2'])]),
- OrderedDict([('struct', 'Base'), ('data', OrderedDict([('enum1', 'TestEnum'), ('name', 'str')]))]),
- OrderedDict([('struct', 'Branch1'), ('data', OrderedDict([('name', 'str')]))]),
- OrderedDict([('struct', 'Branch2'), ('data', OrderedDict([('value', 'int')]))]),
- OrderedDict([('union', 'TestUnion'), ('base', 'Base'), ('discriminator', 'enum1'), ('data', OrderedDict([('value1', 'Branch1'), ('value2', 'Branch2')]))])]
-[{'enum_name': 'TestEnum', 'enum_values': ['value1', 'value2']}]
-[OrderedDict([('struct', 'Base'), ('data', OrderedDict([('enum1', 'TestEnum'), ('name', 'str')]))]),
- OrderedDict([('struct', 'Branch1'), ('data', OrderedDict([('name', 'str')]))]),
- OrderedDict([('struct', 'Branch2'), ('data', OrderedDict([('value', 'int')]))])]
diff --git a/tests/qapi-schema/struct-base-clash-deep.err b/tests/qapi-schema/struct-base-clash-deep.err
new file mode 100644
index 0000000..e3e9f8d
--- /dev/null
+++ b/tests/qapi-schema/struct-base-clash-deep.err
@@ -0,0 +1 @@
+tests/qapi-schema/struct-base-clash-deep.json:7: Member name 'name' clashes with base 'Base'
diff --git a/tests/qapi-schema/struct-base-clash-deep.exit b/tests/qapi-schema/struct-base-clash-deep.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/qapi-schema/struct-base-clash-deep.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/qapi-schema/struct-base-clash-deep.json b/tests/qapi-schema/struct-base-clash-deep.json
new file mode 100644
index 0000000..08c8c9c
--- /dev/null
+++ b/tests/qapi-schema/struct-base-clash-deep.json
@@ -0,0 +1,9 @@
+# we check for no duplicate keys with indirect base
+{ 'struct': 'Base',
+  'data': { 'name': 'str' } }
+{ 'struct': 'Mid',
+  'base': 'Base',
+  'data': { 'value': 'int' } }
+{ 'struct': 'Sub',
+  'base': 'Mid',
+  'data': { 'name': 'str' } }
diff --git a/tests/qapi-schema/struct-base-clash-deep.out b/tests/qapi-schema/struct-base-clash-deep.out
new file mode 100644
index 0000000..e69de29
diff --git a/tests/qapi-schema/struct-base-clash.err b/tests/qapi-schema/struct-base-clash.err
new file mode 100644
index 0000000..3ac37fb
--- /dev/null
+++ b/tests/qapi-schema/struct-base-clash.err
@@ -0,0 +1 @@
+tests/qapi-schema/struct-base-clash.json:4: Member name 'name' clashes with base 'Base'
diff --git a/tests/qapi-schema/struct-base-clash.exit b/tests/qapi-schema/struct-base-clash.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/qapi-schema/struct-base-clash.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/qapi-schema/struct-base-clash.json b/tests/qapi-schema/struct-base-clash.json
new file mode 100644
index 0000000..f2afc9b
--- /dev/null
+++ b/tests/qapi-schema/struct-base-clash.json
@@ -0,0 +1,6 @@
+# we check for no duplicate keys with base
+{ 'struct': 'Base',
+  'data': { 'name': 'str' } }
+{ 'struct': 'Sub',
+  'base': 'Base',
+  'data': { 'name': 'str' } }
