diff --git a/conf.c b/conf.c
index 7f32859..d80233c 100644
--- a/conf.c
+++ b/conf.c
@@ -561,11 +561,6 @@ static int conf_pasta_ns(int *netns_only, char *userns, char *netns,
 		}
 	}
 
-	if (*userns && !*netns) {
-		err("--userns requires --netns or PID");
-		return -EINVAL;
-	}
-
 	/* Attaching to a netns/PID, with no userns given */
 	if (*netns && !*userns)
 		*netns_only = 1;
diff --git a/passt.1 b/passt.1
index 88cc879..83395bc 100644
--- a/passt.1
+++ b/passt.1
@@ -453,8 +453,6 @@ Default is \fBauto\fR.
 Target user namespace to join, as a path. If PID is given, without this option,
 the user namespace will be the one of the corresponding process.
 
-This option requires --netns or a PID to be specified.
-
 .TP
 .BR \-\-netns " " \fIspec
 Target network namespace to join, as a path or a name.  A name is treated as