diff --git a/src/pkg/encoding/json/decode.go b/src/pkg/encoding/json/decode.go
index 87076b53dc0..110c6fd6238 100644
--- a/src/pkg/encoding/json/decode.go
+++ b/src/pkg/encoding/json/decode.go
@@ -496,6 +496,12 @@ func (d *decodeState) object(v reflect.Value) {
 					// Pretend this field doesn't exist.
 					continue
 				}
+				if sf.Anonymous {
+					// Pretend this field doesn't exist,
+					// so that we can do a good job with
+					// these in a later version.
+					continue
+				}
 				// First, tag match
 				tagName, _ := parseTag(tag)
 				if tagName == key {
@@ -963,3 +969,11 @@ func unquoteBytes(s []byte) (t []byte, ok bool) {
 	}
 	return b[0:w], true
 }
+
+// The following is issue 3069.
+
+// BUG(rsc): This package ignores anonymous (embedded) struct fields
+// during encoding and decoding.  A future version may assign meaning
+// to them.  To force an anonymous field to be ignored in all future
+// versions of this package, use an explicit `json:"-"` tag in the struct
+// definition.
diff --git a/src/pkg/encoding/json/decode_test.go b/src/pkg/encoding/json/decode_test.go
index 775becfa7c9..0eec586a9bb 100644
--- a/src/pkg/encoding/json/decode_test.go
+++ b/src/pkg/encoding/json/decode_test.go
@@ -619,3 +619,32 @@ func TestRefUnmarshal(t *testing.T) {
 		t.Errorf("got %+v, want %+v", got, want)
 	}
 }
+
+// Test that anonymous fields are ignored.
+// We may assign meaning to them later.
+func TestAnonymous(t *testing.T) {
+	type S struct {
+		T
+		N int
+	}
+
+	data, err := Marshal(new(S))
+	if err != nil {
+		t.Fatalf("Marshal: %v", err)
+	}
+	want := `{"N":0}`
+	if string(data) != want {
+		t.Fatalf("Marshal = %#q, want %#q", string(data), want)
+	}
+
+	var s S
+	if err := Unmarshal([]byte(`{"T": 1, "T": {"Y": 1}, "N": 2}`), &s); err != nil {
+		t.Fatalf("Unmarshal: %v", err)
+	}
+	if s.N != 2 {
+		t.Fatal("Unmarshal: did not set N")
+	}
+	if s.T.Y != 0 {
+		t.Fatal("Unmarshal: did set T.Y")
+	}
+}
diff --git a/src/pkg/encoding/json/encode.go b/src/pkg/encoding/json/encode.go
index 83e73c09cb4..8a794b79bd5 100644
--- a/src/pkg/encoding/json/encode.go
+++ b/src/pkg/encoding/json/encode.go
@@ -538,6 +538,11 @@ func encodeFields(t reflect.Type) []encodeField {
 		if f.PkgPath != "" {
 			continue
 		}
+		if f.Anonymous {
+			// We want to do a better job with these later,
+			// so for now pretend they don't exist.
+			continue
+		}
 		var ef encodeField
 		ef.i = i
 		ef.tag = f.Name