diff --git a/tests/nexus_workflow_test.go b/tests/nexus_workflow_test.go
index aca43e668a2..6e425025eb8 100644
--- a/tests/nexus_workflow_test.go
+++ b/tests/nexus_workflow_test.go
@@ -31,7 +31,6 @@ import (
 	"net/http"
 	"slices"
 	"strings"
-	"sync/atomic"
 	"testing"
 	"time"
 
@@ -2216,37 +2215,30 @@ func (s *NexusWorkflowTestSuite) TestNexusAsyncOperationWithMultipleCallers() {
 		return "hello " + input, nil
 	}
 
-	opConflictFail := temporalnexus.NewWorkflowRunOperation(
-		"opConflictFail",
-		handlerWf,
-		func(ctx context.Context, input string, opts nexus.StartOperationOptions) (client.StartWorkflowOptions, error) {
-			return client.StartWorkflowOptions{
-				ID: handlerWorkflowID,
-			}, nil
-		},
-	)
-	svc.Register(opConflictFail)
-
-	opConflictUseExisting := temporalnexus.NewWorkflowRunOperation(
-		"opConflictUseExisting",
+	op := temporalnexus.NewWorkflowRunOperation(
+		"op",
 		handlerWf,
 		func(ctx context.Context, input string, opts nexus.StartOperationOptions) (client.StartWorkflowOptions, error) {
+			var conflictPolicy enumspb.WorkflowIdConflictPolicy
+			if input == "conflict-policy-use-existing" {
+				conflictPolicy = enumspb.WORKFLOW_ID_CONFLICT_POLICY_USE_EXISTING
+			}
 			return client.StartWorkflowOptions{
 				ID:                       handlerWorkflowID,
-				WorkflowIDConflictPolicy: enumspb.WORKFLOW_ID_CONFLICT_POLICY_USE_EXISTING,
+				WorkflowIDConflictPolicy: conflictPolicy,
 			}, nil
 		},
 	)
-	svc.Register(opConflictUseExisting)
+	svc.MustRegister(op)
 
 	type CallerWfOutput struct {
-		CntOk  int32
-		CntErr int32
+		CntOk  int
+		CntErr int
 	}
 
-	callerWf := func(ctx workflow.Context, op string, numCalls int) (CallerWfOutput, error) {
-		var cntOk atomic.Int32
-		var cntErr atomic.Int32
+	callerWf := func(ctx workflow.Context, input string, numCalls int) (CallerWfOutput, error) {
+		output := CallerWfOutput{}
+		var retError error
 
 		wg := workflow.NewWaitGroup(ctx)
 		execOpCh := workflow.NewChannel(ctx)
@@ -2256,22 +2248,31 @@ func (s *NexusWorkflowTestSuite) TestNexusAsyncOperationWithMultipleCallers() {
 			wg.Add(1)
 			workflow.Go(ctx, func(ctx workflow.Context) {
 				defer wg.Done()
-				fut := client.ExecuteOperation(ctx, op, "caller", workflow.NexusOperationOptions{})
+				fut := client.ExecuteOperation(ctx, op, input, workflow.NexusOperationOptions{})
 				var exec workflow.NexusOperationExecution
 				err := fut.GetNexusOperationExecution().Get(ctx, &exec)
 				execOpCh.Send(ctx, nil)
 				if err != nil {
-					cntErr.Add(1)
+					output.CntErr++
 					var handlerErr *nexus.HandlerError
-					s.ErrorAs(err, &handlerErr)
-					s.Equal(nexus.HandlerErrorTypeBadRequest, handlerErr.Type)
+					var appErr *temporal.ApplicationError
+					if !errors.As(err, &handlerErr) {
+						retError = err
+					} else if !errors.As(handlerErr, &appErr) {
+						retError = err
+					} else if appErr.Type() != "WorkflowExecutionAlreadyStarted" {
+						retError = err
+					}
 					return
 				}
-				cntOk.Add(1)
+				output.CntOk++
 				var res string
 				err = fut.Get(ctx, &res)
-				s.NoError(err)
-				s.Equal("hello caller", res)
+				if err != nil {
+					retError = err
+				} else if res != "hello "+input {
+					retError = fmt.Errorf("unexpected result from handler workflow: %q", res)
+				}
 			})
 		}
 
@@ -2282,7 +2283,7 @@ func (s *NexusWorkflowTestSuite) TestNexusAsyncOperationWithMultipleCallers() {
 		// signal handler workflow so it will complete
 		workflow.SignalExternalWorkflow(ctx, handlerWorkflowID, "", "terminate", nil).Get(ctx, nil)
 		wg.Wait(ctx)
-		return CallerWfOutput{CntOk: cntOk.Load(), CntErr: cntErr.Load()}, nil
+		return output, retError
 	}
 
 	w.RegisterNexusService(svc)
@@ -2292,42 +2293,41 @@ func (s *NexusWorkflowTestSuite) TestNexusAsyncOperationWithMultipleCallers() {
 	defer w.Stop()
 
 	testCases := []struct {
-		op          string
-		numCalls    int
+		input       string
 		checkOutput func(t *testing.T, numCalls int, res CallerWfOutput)
 	}{
 		{
-			op:       "opConflictFail",
-			numCalls: 5,
+			input: "conflict-policy-fail",
 			checkOutput: func(t *testing.T, numCalls int, res CallerWfOutput) {
 				s.EqualValues(1, res.CntOk)
 				s.EqualValues(numCalls-1, res.CntErr)
 			},
 		},
 		{
-			op:       "opConflictUseExisting",
-			numCalls: 5,
+			input: "conflict-policy-use-existing",
 			checkOutput: func(t *testing.T, numCalls int, res CallerWfOutput) {
 				s.EqualValues(numCalls, res.CntOk)
 			},
 		},
 	}
 
+	// number of concurrent Nexus operation calls
+	numCalls := 5
 	for _, tc := range testCases {
-		s.Run(tc.op, func() {
+		s.Run(tc.input, func() {
 			run, err := s.SdkClient().ExecuteWorkflow(
 				ctx,
 				client.StartWorkflowOptions{
 					TaskQueue: callerTaskQueue,
 				},
 				callerWf,
-				tc.op,
-				tc.numCalls,
+				tc.input,
+				numCalls,
 			)
 			s.NoError(err)
 			var res CallerWfOutput
 			s.NoError(run.Get(ctx, &res))
-			tc.checkOutput(s.T(), tc.numCalls, res)
+			tc.checkOutput(s.T(), numCalls, res)
 		})
 	}
 }