diff --git a/RELNOTES b/RELNOTES
--- a/RELNOTES
+++ b/RELNOTES
@@ -10,6 +10,13 @@
 
 Changes to this file should not be MFCed.
 
+935ffbe06f1d:
+	ps(1)'s default list of processes now comes from matching its effective
+	user ID instead of its real user ID with the effective user ID of all
+	processes, in accordance with POSIX.  As ps(1) itself is not installed
+	setuid, this only affects processes having different real and effective
+	user IDs that launch ps(1) processes.
+
 f0600c41e754-de701f9bdbe0, bc201841d139:
 	mac_do(4) is now considered production-ready and its functionality has
 	been considerably extended at the price of breaking credentials
diff --git a/bin/ps/ps.c b/bin/ps/ps.c
--- a/bin/ps/ps.c
+++ b/bin/ps/ps.c
@@ -503,13 +503,14 @@
 		 */
 		nselectors = 0;
 	else if (nselectors == 0) {
-		/* Default is to request our processes only. */
-		uidlist.l.ptr = malloc(sizeof(uid_t));
-		if (uidlist.l.ptr == NULL)
-			xo_errx(1, "malloc failed");
+		/*
+		 * Default is to request our processes only.  As per POSIX, we
+		 * match processes by their effective user IDs and we use our
+		 * effective user ID as our own identity.
+		 */
+		expand_list(&uidlist);
+		uidlist.l.uids[uidlist.count++] = geteuid();
 		nselectors = 1;
-		uidlist.count = uidlist.maxcount = 1;
-		*uidlist.l.uids = getuid();
 	}
 
 	/*