diff --git a/server/websocket.go b/server/websocket.go
index 607d1bd8..963b9bcb 100644
--- a/server/websocket.go
+++ b/server/websocket.go
@@ -919,13 +919,13 @@ func (s *WebsocketServer) unmarshalAddresses(params []byte) ([]string, bool, err
 	r := WsSubscribeAddressesReq{}
 	err := json.Unmarshal(params, &r)
 	if err != nil {
-		return nil, false, err
+		return nil, false, api.NewAPIError("Invalid subscribeAddresses params", true)
 	}
 	rv := make([]string, len(r.Addresses))
 	for i, a := range r.Addresses {
 		ad, err := s.chainParser.GetAddrDescFromAddress(a)
 		if err != nil {
-			return nil, false, err
+			return nil, false, api.NewAPIError("Invalid address "+strconv.Quote(a)+", "+err.Error(), true)
 		}
 		rv[i] = string(ad)
 	}
diff --git a/server/websocket_unmarshal_test.go b/server/websocket_unmarshal_test.go
new file mode 100644
index 00000000..be2640cf
--- /dev/null
+++ b/server/websocket_unmarshal_test.go
@@ -0,0 +1,32 @@
+//go:build unittest
+
+package server
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/trezor/blockbook/api"
+	"github.com/trezor/blockbook/bchain/coins/eth"
+)
+
+func TestUnmarshalAddressesReturnsPublicAPIError(t *testing.T) {
+	s := &WebsocketServer{
+		chainParser: eth.NewEthereumParser(0, false),
+	}
+
+	_, _, err := s.unmarshalAddresses([]byte(`{"addresses":[""]}`))
+	if err == nil {
+		t.Fatal("expected error")
+	}
+	apiErr, ok := err.(*api.APIError)
+	if !ok {
+		t.Fatalf("expected *api.APIError, got %T", err)
+	}
+	if !apiErr.Public {
+		t.Fatal("expected public api error")
+	}
+	if !strings.Contains(apiErr.Error(), "Address missing") {
+		t.Fatalf("unexpected error message %q", apiErr.Error())
+	}
+}