diff --git a/bridge/src/main/scala/protocbridge/frontend/SocketBasedPluginFrontend.scala b/bridge/src/main/scala/protocbridge/frontend/SocketBasedPluginFrontend.scala
index 6d1dd59..d969525 100644
--- a/bridge/src/main/scala/protocbridge/frontend/SocketBasedPluginFrontend.scala
+++ b/bridge/src/main/scala/protocbridge/frontend/SocketBasedPluginFrontend.scala
@@ -2,7 +2,7 @@ package protocbridge.frontend
 
 import protocbridge.{ExtraEnv, ProtocCodeGenerator}
 
-import java.net.ServerSocket
+import java.net.{InetAddress, ServerSocket}
 import java.nio.file.{Files, Path}
 import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.{Future, blocking}
@@ -10,13 +10,19 @@ import scala.concurrent.{Future, blocking}
 /** PluginFrontend for Windows and macOS where a server socket is used.
   */
 abstract class SocketBasedPluginFrontend extends PluginFrontend {
+
   case class InternalState(serverSocket: ServerSocket, shellScript: Path)
 
   override def prepare(
       plugin: ProtocCodeGenerator,
       env: ExtraEnv
   ): (Path, InternalState) = {
-    val ss = new ServerSocket(0) // Bind to any available port.
+
+    /** we need to specify an address, otherwise it uses ANY (*.* in netstat)
+      * which does not conflict with existing 'localhost' sockets on macos,
+      * resulting in a conflict later on in MacPluginFrontend
+      */
+    val ss = new ServerSocket(0, 50, InetAddress.getByName("127.0.0.1"))
     val sh = createShellScript(ss.getLocalPort)
 
     Future {