diff --git a/api/agent/pure_runner.go b/api/agent/pure_runner.go
index e49caa06c..00973eeee 100644
--- a/api/agent/pure_runner.go
+++ b/api/agent/pure_runner.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"crypto/tls"
 	"crypto/x509"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -537,7 +538,12 @@ func (pr *pureRunner) handleTryCall(tc *runner.TryCall, state *callHandle) error
 
 	state.c = agent_call.(*call)
 	if tc.SlotHashId != "" {
-		state.c.slotHashId = tc.SlotHashId
+		hashId, err := hex.DecodeString(tc.SlotHashId)
+		if err != nil {
+			state.enqueueCallResponse(err)
+			return err
+		}
+		state.c.slotHashId = string(hashId[:])
 	}
 	state.allocatedTime = strfmt.DateTime(time.Now())
 	pr.spawnSubmit(state)
diff --git a/api/agent/runner_client.go b/api/agent/runner_client.go
index 7ac67eae8..1b8c56008 100644
--- a/api/agent/runner_client.go
+++ b/api/agent/runner_client.go
@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"io"
@@ -126,7 +127,7 @@ func (r *gRPCRunner) TryExec(ctx context.Context, call pool.RunnerCall) (bool, e
 	// send explicit NACK
 	err = runnerConnection.Send(&pb.ClientMsg{Body: &pb.ClientMsg_Try{Try: &pb.TryCall{
 		ModelsCallJson: string(modelJSON),
-		SlotHashId:     call.SlotHashId(),
+		SlotHashId:     hex.EncodeToString([]byte(call.SlotHashId())),
 	}}})
 	if err != nil {
 		logrus.WithError(err).Error("Failed to send message to runner node")