diff --git a/ChangeLog b/ChangeLog
index b9d8dc9ba..e55d27f3d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2022-04-13 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/NSSocketPort.m: set listening socket into non-blocking mode
+	if possible, so if multiple threads are using the same port we don't
+	get one thread blocked wating for an accept which was handled by
+	another one.
+
 2022-03-23 Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/NSTimer.m: wrap call to block in exception handler (bug #289)
diff --git a/Source/NSSocketPort.m b/Source/NSSocketPort.m
index 953b8fc83..ea6523d3a 100644
--- a/Source/NSSocketPort.m
+++ b/Source/NSSocketPort.m
@@ -1864,6 +1864,23 @@ static Class		tcpPortClass;
 	    {
 #if	defined(_WIN32)
               int rc;
+
+#else
+              int e;
+              if ((e = fcntl(desc, F_GETFL, 0)) >= 0)
+                {
+                  e |= NBLK_OPT;
+                  if (fcntl(desc, F_SETFL, e) < 0)
+                    {
+                      NSLog(@"unable to set non-blocking mode on %d - %@",
+                        desc, [NSError _last]);
+                    }
+                }
+              else
+                {
+                  NSLog(@"unable to get/set non-blocking mode on %d - %@",
+                    desc, [NSError _last]);
+                }
 #endif
 	      /*
 	       * Set up the listening descriptor and the actual TCP port