diff --git a/hivesim/hive_test.go b/hivesim/hive_test.go
index 48863b109e..64c5053cdb 100644
--- a/hivesim/hive_test.go
+++ b/hivesim/hive_test.go
@@ -400,9 +400,9 @@ func TestStartClientInitialNetworks(t *testing.T) {
 }
 
 func newFakeAPI(hooks *fakes.BackendHooks) (*libhive.TestManager, *httptest.Server) {
-	defs := map[string]*libhive.ClientDefinition{
-		"client-1": {Name: "client-1", Image: "/ignored/in/api", Version: "client-1-version", Meta: libhive.ClientMetadata{Roles: []string{"eth1"}}},
-		"client-2": {Name: "client-2", Image: "/not/exposed/", Version: "client-2-version", Meta: libhive.ClientMetadata{Roles: []string{"beacon"}}},
+	defs := []*libhive.ClientDefinition{
+		{Name: "client-1", Image: "/ignored/in/api", Version: "client-1-version", Meta: libhive.ClientMetadata{Roles: []string{"eth1"}}},
+		{Name: "client-2", Image: "/not/exposed/", Version: "client-2-version", Meta: libhive.ClientMetadata{Roles: []string{"beacon"}}},
 	}
 	env := libhive.SimEnv{}
 	backend := fakes.NewContainerBackend(hooks)
diff --git a/internal/libhive/api.go b/internal/libhive/api.go
index d0a051e3fa..06c89876d7 100644
--- a/internal/libhive/api.go
+++ b/internal/libhive/api.go
@@ -10,7 +10,6 @@ import (
 	"net/http"
 	"path"
 	"path/filepath"
-	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -61,14 +60,7 @@ type simAPI struct {
 
 // getClientTypes returns all known client types.
 func (api *simAPI) getClientTypes(w http.ResponseWriter, r *http.Request) {
-	clients := make([]*ClientDefinition, 0, len(api.tm.clientDefs))
-	for _, def := range api.tm.clientDefs {
-		clients = append(clients, def)
-	}
-	sort.Slice(clients, func(i, j int) bool {
-		return clients[i].Name < clients[j].Name
-	})
-	serveJSON(w, clients)
+	serveJSON(w, api.tm.clientDefs)
 }
 
 // startSuite starts a suite.
@@ -332,11 +324,12 @@ func (api *simAPI) checkClient(req *simapi.NodeConfig) (*ClientDefinition, error
 	if req.Client == "" {
 		return nil, errors.New("missing client type in start request")
 	}
-	def, ok := api.tm.clientDefs[req.Client]
-	if !ok {
-		return nil, errors.New("unknown client type in start request")
+	for _, client := range api.tm.clientDefs {
+		if client.Name == req.Client {
+			return client, nil
+		}
 	}
-	return def, nil
+	return nil, errors.New("unknown client type in start request")
 }
 
 // checkClientNetworks pre-checks the existence of initial networks for a client container.
diff --git a/internal/libhive/run.go b/internal/libhive/run.go
index 37e0f8bd11..42b985e834 100644
--- a/internal/libhive/run.go
+++ b/internal/libhive/run.go
@@ -30,7 +30,7 @@ type Runner struct {
 
 	// This holds the image names of all built simulators.
 	simImages  map[string]string
-	clientDefs map[string]*ClientDefinition
+	clientDefs []*ClientDefinition
 }
 
 func NewRunner(inv Inventory, b Builder, cb ContainerBackend) *Runner {
@@ -58,11 +58,11 @@ func (r *Runner) buildClients(ctx context.Context, clientList []ClientDesignator
 		return errors.New("client list is empty, cannot simulate")
 	}
 
-	r.clientDefs = make(map[string]*ClientDefinition, len(clientList))
+	r.clientDefs = make([]*ClientDefinition, len(clientList))
 
 	var anyBuilt bool
 	log15.Info(fmt.Sprintf("building %d clients...", len(clientList)))
-	for _, client := range clientList {
+	for i, client := range clientList {
 		image, err := r.builder.BuildClientImage(ctx, client)
 		if err != nil {
 			continue
@@ -72,7 +72,7 @@ func (r *Runner) buildClients(ctx context.Context, clientList []ClientDesignator
 		if err != nil {
 			log15.Warn("can't read version info of "+client.Client, "image", image, "err", err)
 		}
-		r.clientDefs[client.Name()] = &ClientDefinition{
+		r.clientDefs[i] = &ClientDefinition{
 			Name:    client.Name(),
 			Version: strings.TrimSpace(string(version)),
 			Image:   image,
@@ -117,8 +117,11 @@ func (r *Runner) RunDevMode(ctx context.Context, env SimEnv, endpoint string) er
 	if err := createWorkspace(env.LogDir); err != nil {
 		return err
 	}
-
-	tm := NewTestManager(env, r.container, r.clientDefs)
+	clientDefs := make([]*ClientDefinition, 0)
+	for _, def := range r.clientDefs {
+		clientDefs = append(clientDefs, def)
+	}
+	tm := NewTestManager(env, r.container, clientDefs)
 	defer func() {
 		if err := tm.Terminate(); err != nil {
 			log15.Error("could not terminate test manager", "error", err)
@@ -159,19 +162,23 @@ HIVE_SIMULATOR=http://%v
 func (r *Runner) run(ctx context.Context, sim string, env SimEnv) (SimResult, error) {
 	log15.Info(fmt.Sprintf("running simulation: %s", sim))
 
-	clientDefs := make(map[string]*ClientDefinition)
+	clientDefs := make([]*ClientDefinition, 0)
 	if env.ClientList == nil {
 		// Unspecified, make all clients available.
-		for name, def := range r.clientDefs {
-			clientDefs[name] = def
-		}
+		clientDefs = append(clientDefs, r.clientDefs...)
 	} else {
 		for _, client := range env.ClientList {
-			def, ok := r.clientDefs[client.Client]
-			if !ok {
+			found := false
+			for _, def := range r.clientDefs {
+				if def.Name == client.Client {
+					clientDefs = append(clientDefs, def)
+					found = true
+					break
+				}
+			}
+			if !found {
 				return SimResult{}, fmt.Errorf("unknown client %q in simulation client list", client.Client)
 			}
-			clientDefs[client.Client] = def
 		}
 	}
 
diff --git a/internal/libhive/testmanager.go b/internal/libhive/testmanager.go
index beee5ff621..18d5ffedae 100644
--- a/internal/libhive/testmanager.go
+++ b/internal/libhive/testmanager.go
@@ -61,7 +61,7 @@ type SimResult struct {
 type TestManager struct {
 	config     SimEnv
 	backend    ContainerBackend
-	clientDefs map[string]*ClientDefinition
+	clientDefs []*ClientDefinition
 
 	simContainerID string
 	simLogFile     string
@@ -80,7 +80,7 @@ type TestManager struct {
 	results           map[TestSuiteID]*TestSuite
 }
 
-func NewTestManager(config SimEnv, b ContainerBackend, clients map[string]*ClientDefinition) *TestManager {
+func NewTestManager(config SimEnv, b ContainerBackend, clients []*ClientDefinition) *TestManager {
 	return &TestManager{
 		clientDefs:        clients,
 		config:            config,