diff --git a/cmd/shadowsocks-go-domain-set-converter/main.go b/cmd/shadowsocks-go-domain-set-converter/main.go
index c84a1be..431a03c 100644
--- a/cmd/shadowsocks-go-domain-set-converter/main.go
+++ b/cmd/shadowsocks-go-domain-set-converter/main.go
@@ -54,41 +54,41 @@ func main() {
 	}
 
 	if inCount != 1 {
-		fmt.Println("Exactly one of -inDlc, -inText, -inGob must be specified.")
+		fmt.Fprintln(os.Stderr, "Exactly one of -inDlc, -inText, -inGob must be specified.")
 		flag.Usage()
 		os.Exit(1)
 	}
 
 	if *outText == "" && *outGob == "" {
-		fmt.Println("Specify output file paths with -outText and/or -outGob.")
+		fmt.Fprintln(os.Stderr, "Specify output file paths with -outText and/or -outGob.")
 		flag.Usage()
 		os.Exit(1)
 	}
 
 	data, err := mmap.ReadFile[string](inPath)
 	if err != nil {
-		fmt.Println(err)
+		fmt.Fprintln(os.Stderr, "Failed to read input file:", err)
 		os.Exit(1)
 	}
 	defer mmap.Unmap(data)
 
 	dsb, err := inFunc(data)
 	if err != nil {
-		fmt.Println(err)
+		fmt.Fprintln(os.Stderr, "Failed to parse input file:", err)
 		return
 	}
 
 	if *outText != "" {
 		fout, err := os.Create(*outText)
 		if err != nil {
-			fmt.Println(err)
+			fmt.Fprintln(os.Stderr, "Failed to create output file:", err)
 			return
 		}
 		defer fout.Close()
 
 		err = dsb.WriteText(fout)
 		if err != nil {
-			fmt.Println(err)
+			fmt.Fprintln(os.Stderr, "Failed to write output file:", err)
 			return
 		}
 	}
@@ -96,14 +96,14 @@ func main() {
 	if *outGob != "" {
 		fout, err := os.Create(*outGob)
 		if err != nil {
-			fmt.Println(err)
+			fmt.Fprintln(os.Stderr, "Failed to create output file:", err)
 			return
 		}
 		defer fout.Close()
 
 		err = dsb.WriteGob(fout)
 		if err != nil {
-			fmt.Println(err)
+			fmt.Fprintln(os.Stderr, "Failed to write output file:", err)
 			return
 		}
 	}
diff --git a/cmd/shadowsocks-go/main.go b/cmd/shadowsocks-go/main.go
index 349cf6b..48a706f 100644
--- a/cmd/shadowsocks-go/main.go
+++ b/cmd/shadowsocks-go/main.go
@@ -33,7 +33,7 @@ func main() {
 	flag.Parse()
 
 	if confPath == "" {
-		fmt.Println("Missing -confPath <path>.")
+		fmt.Fprintln(os.Stderr, "Missing -confPath <path>.")
 		flag.Usage()
 		os.Exit(1)
 	}
@@ -54,7 +54,7 @@ func main() {
 		zc = zap.NewDevelopmentConfig()
 	default:
 		if err := jsonhelper.LoadAndDecodeDisallowUnknownFields(zapConf, &zc); err != nil {
-			fmt.Println(err)
+			fmt.Fprintln(os.Stderr, "Failed to load zap logger config:", err)
 			os.Exit(1)
 		}
 	}
@@ -65,7 +65,7 @@ func main() {
 
 	logger, err := zc.Build()
 	if err != nil {
-		fmt.Println(err)
+		fmt.Fprintln(os.Stderr, "Failed to build logger:", err)
 		os.Exit(1)
 	}
 	defer logger.Sync()