diff --git a/proxy/lib/snowflake.go b/proxy/lib/snowflake.go
index 6891be0..f8a0f2c 100644
--- a/proxy/lib/snowflake.go
+++ b/proxy/lib/snowflake.go
@@ -354,7 +354,10 @@ func (sf *SnowflakeProxy) makeWebRTCAPI() *webrtc.API {
 	settingsEngine := webrtc.SettingEngine{}
 
 	if sf.EphemeralMinPort != 0 && sf.EphemeralMaxPort != 0 {
-		settingsEngine.SetEphemeralUDPPortRange(sf.EphemeralMinPort, sf.EphemeralMaxPort)
+		err := settingsEngine.SetEphemeralUDPPortRange(sf.EphemeralMinPort, sf.EphemeralMaxPort)
+		if err != nil {
+			log.Fatal("Invalid port range: min > max")
+		}
 	}
 
 	settingsEngine.SetICEMulticastDNSMode(ice.MulticastDNSModeDisabled)
diff --git a/proxy/main.go b/proxy/main.go
index 38c07b0..146a1f3 100644
--- a/proxy/main.go
+++ b/proxy/main.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"flag"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
@@ -31,7 +30,7 @@ func main() {
 	SummaryInterval := flag.Duration("summary-interval", time.Hour,
 		"the time interval to output summary, 0s disables summaries. Valid time units are \"s\", \"m\", \"h\". ")
 	verboseLogging := flag.Bool("verbose", false, "increase log verbosity")
-	ephemeralPortsRangeFlag := flag.String("ephemeral-ports-range", "ICE UDP ephemeral ports range (format:\"[min]:[max]\")", "")
+	ephemeralPortsRangeFlag := flag.String("ephemeral-ports-range", "", "ICE UDP ephemeral ports range (format:\"<min>:<max>\")")
 
 	var ephemeralPortsRange []uint16 = []uint16{0, 0}
 
@@ -52,10 +51,14 @@ func main() {
 				log.Fatal(err)
 			}
 
-			ephemeralPortsRange = []uint16{uint16(ephemeralMinPort), uint16(ephemeralMaxPort)}
-		}
+			if ephemeralMinPort == 0 || ephemeralMaxPort == 0 {
+				log.Fatal("Ephemeral port cannot be zero")
+			}
 
-		fmt.Printf("Bad range port format: %v", ephemeralPortsRangeFlag)
+			ephemeralPortsRange = []uint16{uint16(ephemeralMinPort), uint16(ephemeralMaxPort)}
+		} else {
+			log.Fatalf("Bad range port format: %v", *ephemeralPortsRangeFlag)
+		}
 	}
 
 	proxy := sf.SnowflakeProxy{