diff --git a/rfq/oracle.go b/rfq/oracle.go
index 50ce9c522..d2423b553 100644
--- a/rfq/oracle.go
+++ b/rfq/oracle.go
@@ -221,11 +221,14 @@ func (r *RpcPriceOracle) QueryAskPrice(ctx context.Context,
 		return nil, fmt.Errorf("asset ID is nil")
 	}
 
-	// Construct query request.
-	var subjectAssetId []byte
-	copy(subjectAssetId, assetId[:])
+	var (
+		subjectAssetId = make([]byte, 32)
+		paymentAssetId = make([]byte, 32)
+	)
 
-	paymentAssetId := make([]byte, 32)
+	// The payment asset ID is BTC, so we leave it at all zeroes. We only
+	// set the subject asset ID.
+	copy(subjectAssetId, assetId[:])
 
 	// Construct the RPC rate tick hint.
 	var rateTickHint *oraclerpc.RateTick
@@ -303,11 +306,14 @@ func (r *RpcPriceOracle) QueryBidPrice(ctx context.Context, assetId *asset.ID,
 		return nil, fmt.Errorf("asset ID is nil")
 	}
 
-	// Construct query request.
-	var subjectAssetId []byte
-	copy(subjectAssetId, assetId[:])
+	var (
+		subjectAssetId = make([]byte, 32)
+		paymentAssetId = make([]byte, 32)
+	)
 
-	paymentAssetId := make([]byte, 32)
+	// The payment asset ID is BTC, so we leave it at all zeroes. We only
+	// set the subject asset ID.
+	copy(subjectAssetId, assetId[:])
 
 	req := &oraclerpc.QueryRateTickRequest{
 		TransactionType: oraclerpc.TransactionType_PURCHASE,
diff --git a/rfq/oracle_test.go b/rfq/oracle_test.go
index 58a500642..3f1637798 100644
--- a/rfq/oracle_test.go
+++ b/rfq/oracle_test.go
@@ -1,6 +1,7 @@
 package rfq
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"net"
@@ -43,6 +44,11 @@ func (p *mockRpcPriceOracleServer) QueryRateTick(_ context.Context,
 		ExpiryTimestamp: uint64(expiry),
 	}
 
+	err := validateRateTickRequest(req)
+	if err != nil {
+		return nil, err
+	}
+
 	// If a rate tick hint is provided, return it as the rate tick.
 	if req.RateTickHint != nil {
 		rateTick.Rate = req.RateTickHint.Rate
@@ -58,6 +64,32 @@ func (p *mockRpcPriceOracleServer) QueryRateTick(_ context.Context,
 	}, nil
 }
 
+// validateRateTickRequest validates the given rate tick request.
+func validateRateTickRequest(req *priceoraclerpc.QueryRateTickRequest) error {
+	var zeroAssetID [32]byte
+	if req.SubjectAsset == nil {
+		return fmt.Errorf("subject asset must be specified")
+	}
+	if len(req.SubjectAsset.GetAssetId()) != 32 {
+		return fmt.Errorf("invalid subject asset ID length")
+	}
+	if bytes.Equal(req.SubjectAsset.GetAssetId(), zeroAssetID[:]) {
+		return fmt.Errorf("subject asset ID must NOT be all zero")
+	}
+
+	if req.PaymentAsset == nil {
+		return fmt.Errorf("payment asset must be specified")
+	}
+	if len(req.PaymentAsset.GetAssetId()) != 32 {
+		return fmt.Errorf("invalid payment asset ID length")
+	}
+	if !bytes.Equal(req.PaymentAsset.GetAssetId(), zeroAssetID[:]) {
+		return fmt.Errorf("payment asset ID must be all zero")
+	}
+
+	return nil
+}
+
 // startBackendRPC starts the given RPC server and blocks until the server is
 // shut down.
 func startBackendRPC(grpcServer *grpc.Server) error {
@@ -95,7 +127,7 @@ func runQueryAskPriceTest(t *testing.T, tc *testCaseQueryAskPrice) {
 	defer backendService.Stop()
 
 	// Wait for the server to start.
-	time.Sleep(2 * time.Second)
+	time.Sleep(200 * time.Millisecond)
 
 	// Create a new RPC price oracle client and connect to the mock service.
 	serviceAddr := fmt.Sprintf("rfqrpc://%s", testServiceAddress)