diff --git a/config_runtime.go b/config_runtime.go
index 3d842ee..ac185c2 100644
--- a/config_runtime.go
+++ b/config_runtime.go
@@ -46,11 +46,16 @@ func (c *Config) Validate() error {
 	if c == nil {
 		return errors.New("config is nil")
 	}
-	if c.Mode != "" && c.Mode != "nicehash" && c.Mode != "simple" {
+	if strings.TrimSpace(c.Mode) == "" {
+		return errors.New("mode is empty")
+	}
+	if c.Mode != "nicehash" && c.Mode != "simple" {
 		return errors.New("mode is invalid")
 	}
-	if c.Workers != "" &&
-		c.Workers != WorkersByRigID &&
+	if strings.TrimSpace(string(c.Workers)) == "" {
+		return errors.New("workers mode is empty")
+	}
+	if c.Workers != WorkersByRigID &&
 		c.Workers != WorkersByUser &&
 		c.Workers != WorkersByPass &&
 		c.Workers != WorkersByPassword &&
@@ -101,12 +106,13 @@ func (w *ConfigWatcher) Start() {
 		return
 	}
 
+	if info, errorValue := os.Stat(w.path); errorValue == nil {
+		w.lastModifiedAt = info.ModTime()
+	}
+
 	go func() {
 		ticker := time.NewTicker(time.Second)
 		defer ticker.Stop()
-		if info, errorValue := os.Stat(w.path); errorValue == nil {
-			w.lastModifiedAt = info.ModTime()
-		}
 
 		for {
 			select {
diff --git a/config_runtime_test.go b/config_runtime_test.go
index fd78fde..52d1609 100644
--- a/config_runtime_test.go
+++ b/config_runtime_test.go
@@ -8,9 +8,10 @@ import (
 
 func TestConfig_Validate_Good(t *testing.T) {
 	cfg := &Config{
-		Mode:  "nicehash",
-		Bind:  []BindAddr{{Host: "127.0.0.1", Port: 3333}},
-		Pools: []PoolConfig{{URL: "pool-a:3333", Enabled: true}},
+		Mode:    "nicehash",
+		Workers: WorkersByRigID,
+		Bind:    []BindAddr{{Host: "127.0.0.1", Port: 3333}},
+		Pools:   []PoolConfig{{URL: "pool-a:3333", Enabled: true}},
 	}
 
 	if errorValue := cfg.Validate(); errorValue != nil {
@@ -30,6 +31,17 @@ func TestConfig_Validate_Bad(t *testing.T) {
 	}
 }
 
+func TestConfig_Validate_EmptyMode(t *testing.T) {
+	cfg := &Config{
+		Bind:  []BindAddr{{Host: "127.0.0.1", Port: 3333}},
+		Pools: []PoolConfig{{URL: "pool-a:3333", Enabled: true}},
+	}
+
+	if errorValue := cfg.Validate(); errorValue == nil {
+		t.Fatal("expected empty mode to fail validation")
+	}
+}
+
 func TestConfig_Validate_Ugly(t *testing.T) {
 	cfg := &Config{
 		Mode:    "simple",
@@ -43,6 +55,18 @@ func TestConfig_Validate_Ugly(t *testing.T) {
 	}
 }
 
+func TestConfig_Validate_EmptyWorkers(t *testing.T) {
+	cfg := &Config{
+		Mode:  "simple",
+		Bind:  []BindAddr{{Host: "127.0.0.1", Port: 3333}},
+		Pools: []PoolConfig{{URL: "pool-a:3333", Enabled: true}},
+	}
+
+	if errorValue := cfg.Validate(); errorValue == nil {
+		t.Fatal("expected empty workers mode to fail validation")
+	}
+}
+
 func TestConfig_Validate_EnabledPoolURL(t *testing.T) {
 	cfg := &Config{
 		Mode:  "simple",
@@ -57,7 +81,7 @@ func TestConfig_Validate_EnabledPoolURL(t *testing.T) {
 
 func TestConfigWatcher_Start_Bad(t *testing.T) {
 	path := t.TempDir() + "/config.json"
-	errorValue := os.WriteFile(path, []byte(`{"bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-a:3333","enabled":true}]}`), 0o644)
+	errorValue := os.WriteFile(path, []byte(`{"mode":"nicehash","workers":"rig-id","bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-a:3333","enabled":true}]}`), 0o644)
 	if errorValue != nil {
 		t.Fatal(errorValue)
 	}
@@ -69,7 +93,7 @@ func TestConfigWatcher_Start_Bad(t *testing.T) {
 	watcher.Start()
 	defer watcher.Stop()
 
-	errorValue = os.WriteFile(path, []byte(`{"bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-b:3333","enabled":true}]}`), 0o644)
+	errorValue = os.WriteFile(path, []byte(`{"mode":"nicehash","workers":"rig-id","bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-b:3333","enabled":true}]}`), 0o644)
 	if errorValue != nil {
 		t.Fatal(errorValue)
 	}
diff --git a/splitter/simple/splitter_test.go b/splitter/simple/splitter_test.go
index 06174da..0496954 100644
--- a/splitter/simple/splitter_test.go
+++ b/splitter/simple/splitter_test.go
@@ -166,7 +166,7 @@ func TestSimpleMapper_JobForID_BadClientID(t *testing.T) {
 
 func TestConfigWatcher_Start_Ugly(t *testing.T) {
 	path := t.TempDir() + "/config.json"
-	errorValue := os.WriteFile(path, []byte(`{"bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-a:3333","enabled":true}]}`), 0o644)
+	errorValue := os.WriteFile(path, []byte(`{"mode":"simple","workers":"rig-id","bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-a:3333","enabled":true}]}`), 0o644)
 	if errorValue != nil {
 		t.Fatal(errorValue)
 	}
@@ -184,7 +184,7 @@ func TestConfigWatcher_Start_Ugly(t *testing.T) {
 	case <-time.After(1200 * time.Millisecond):
 	}
 
-	if errorValue = os.WriteFile(path, []byte(`{"bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-b:3333","enabled":true}]}`), 0o644); errorValue != nil {
+	if errorValue = os.WriteFile(path, []byte(`{"mode":"simple","workers":"rig-id","bind":[{"host":"127.0.0.1","port":3333}],"pools":[{"url":"pool-b:3333","enabled":true}]}`), 0o644); errorValue != nil {
 		t.Fatal(errorValue)
 	}