diff --git a/accounting/grpc/service_frostfs.pb.go b/accounting/grpc/service_frostfs.pb.go
index b70fd275..4f113030 100644
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diff --git a/accounting/grpc/types_frostfs.pb.go b/accounting/grpc/types_frostfs.pb.go
index 182705e6..0ae770b3 100644
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diff --git a/acl/grpc/types_frostfs.pb.go b/acl/grpc/types_frostfs.pb.go
index b0551673..57e16821 100644
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diff --git a/ape/grpc/types_frostfs.pb.go b/ape/grpc/types_frostfs.pb.go
index e19d9f69..7967e131 100644
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diff --git a/apemanager/grpc/service_frostfs.pb.go b/apemanager/grpc/service_frostfs.pb.go
index 99abeb29..2a30850a 100644
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diff --git a/container/grpc/service_frostfs.pb.go b/container/grpc/service_frostfs.pb.go
index ffdc7306..4ccb595e 100644
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diff --git a/container/grpc/types_frostfs.pb.go b/container/grpc/types_frostfs.pb.go
index 3010eb06..9db07ed3 100644
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diff --git a/lock/grpc/types_frostfs.pb.go b/lock/grpc/types_frostfs.pb.go
index 58be8957..33f22c58 100644
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diff --git a/netmap/grpc/service_frostfs.pb.go b/netmap/grpc/service_frostfs.pb.go
index 3d628558..4d530313 100644
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diff --git a/netmap/grpc/types_frostfs.pb.go b/netmap/grpc/types_frostfs.pb.go
index 43af1037..d082910e 100644
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diff --git a/object/grpc/service_frostfs.pb.go b/object/grpc/service_frostfs.pb.go
index 188d0326..2434bd3b 100644
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diff --git a/object/grpc/types_frostfs.pb.go b/object/grpc/types_frostfs.pb.go
index 9fc27697..5b1eb2c3 100644
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diff --git a/refs/grpc/types_frostfs.pb.go b/refs/grpc/types_frostfs.pb.go
index 5f35eba2..869620f8 100644
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diff --git a/session/grpc/service_frostfs.pb.go b/session/grpc/service_frostfs.pb.go
index aa42ee8f..a3f01112 100644
Binary files a/session/grpc/service_frostfs.pb.go and b/session/grpc/service_frostfs.pb.go differ
diff --git a/session/grpc/types_frostfs.pb.go b/session/grpc/types_frostfs.pb.go
index c92ab28b..58807fef 100644
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diff --git a/status/grpc/types_frostfs.pb.go b/status/grpc/types_frostfs.pb.go
index 29dfebe5..7581dbe9 100644
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diff --git a/tombstone/grpc/types_frostfs.pb.go b/tombstone/grpc/types_frostfs.pb.go
index f7bc48c4..79afdfcd 100644
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diff --git a/util/proto/test/custom/test_frostfs.pb.go b/util/proto/test/custom/test_frostfs.pb.go
index 005d6d11..03f3ece6 100644
Binary files a/util/proto/test/custom/test_frostfs.pb.go and b/util/proto/test/custom/test_frostfs.pb.go differ
diff --git a/util/protogen/internalgengo/json.go b/util/protogen/internalgengo/json.go
index 95a06d59..ec70155b 100644
--- a/util/protogen/internalgengo/json.go
+++ b/util/protogen/internalgengo/json.go
@@ -147,8 +147,11 @@ func emitJSONMarshal(g *protogen.GeneratedFile, msg *protogen.Message) {
 	g.P("func (x *", msg.GoIdent.GoName, ") MarshalEasyJSON(out *", jwriterPackage.Ident("Writer"), ") {")
 	g.P(`if x == nil { out.RawString("null"); return }`)
 
+	if len(msg.Fields) != 0 {
+		g.P("first := true")
+	}
 	g.P("out.RawByte('{')")
-	for i, f := range msg.Fields {
+	for _, f := range msg.Fields {
 		if f.Oneof != nil {
 			if f.Oneof.Fields[0] != f {
 				continue
@@ -157,29 +160,35 @@ func emitJSONMarshal(g *protogen.GeneratedFile, msg *protogen.Message) {
 			g.P("switch xx := x.", f.Oneof.GoName, ".(type) {")
 			for _, ff := range f.Oneof.Fields {
 				g.P("case *", ff.GoIdent, ":")
-				emitJSONFieldWrite(g, ff, "xx", i == 0)
+				emitJSONFieldWrite(g, ff, "xx")
 			}
 			g.P("}")
 			continue
 		}
-		emitJSONFieldWrite(g, f, "x", i == 0)
+		emitJSONFieldWrite(g, f, "x")
 	}
 	g.P("out.RawByte('}')")
 	g.P("}")
 }
 
-func emitJSONFieldWrite(g *protogen.GeneratedFile, f *protogen.Field, name string, first bool) {
+func emitJSONFieldWrite(g *protogen.GeneratedFile, f *protogen.Field, name string) {
 	g.P("{")
 	defer g.P("}")
 
-	g.P("const prefix string = ", `",\"`, fieldJSONName(f), `\":"`)
-	if first {
-		g.P("out.RawString(prefix[1:])")
-	} else {
-		g.P("out.RawString(prefix)")
-	}
-
 	selector := name + "." + f.GoName
+
+	isNotDefault := notNil
+	if f.Desc.IsList() {
+		isNotDefault = notEmpty
+	} else if f.Desc.Kind() != protoreflect.MessageKind {
+		_, isNotDefault = easyprotoKindInfo(f.Desc.Kind())
+	}
+	g.P("if ", isNotDefault(selector), "{")
+	defer g.P("}")
+
+	g.P("if !first { out.RawByte(','); } else { first = false; }")
+	g.P("const prefix string = ", `"\"`, fieldJSONName(f), `\":"`)
+	g.P("out.RawString(prefix)")
 	if f.Desc.IsList() {
 		selector += "[i]"
 		g.P("out.RawByte('[')")