diff --git a/bin/ps/ps.1 b/bin/ps/ps.1
index e3681a5641c..d823df48c09 100644
--- a/bin/ps/ps.1
+++ b/bin/ps/ps.1
@@ -127,9 +127,7 @@ First, options
 .Fl o
 and
 .Fl O
-add columns with data corresponding to the explicitly passed keywords and, for
-.Fl O ,
-additionally the same columns as in the default display.
+add columns with data corresponding to the explicitly passed keywords.
 Available keywords are documented in the
 .Sx KEYWORDS
 section below.
@@ -323,15 +321,15 @@ terminal and process ID.
 Extract the name list from the specified system instead of the default,
 which is the kernel image the system has booted from.
 .It Fl O
-On first occurence, add all columns of the default display
-.Po
-as if by
-.Fl o
-.Pc
-and insert just after the process ID column in that default display the columns
-associated with the passed space- or comma-separated list of keywords.
-On next occurences, just insert the keywords of the passed list, as if by
-.Fl o .
+Save passed columns in a separate list that in the end is grafted just after the
+display's first occurence of the process ID column as specified by other
+options, or the default display if there is none.
+If the display prepared by other options does not include a process ID column,
+the list is inserted at start of the display.
+Further occurences of
+.Fl O
+append to the to-be-grafted list of columns.
+This option takes a space- or comma-separated list of keywords.
 The last keyword in the list may be appended with an equals sign
 .Pq Ql =
 as explained for option
@@ -1023,15 +1021,6 @@ implementation (for other BSDs, illumos or Linux) behaves like this.
 For all these reasons, the behavior is expected to be changed soon to using the
 effective user ID instead.
 .Pp
-Option
-.Fl O
-has not been designed to be combined with other options as it forces insertion
-of the default display on first occurence.
-Moreover, these default display's columns are then not considered for duplicate
-elimination, contrary to those of canned displays.
-Finally, columns requested through multiple occurences are not grouped together,
-as one may naturally expect.
-.Pp
 The
 .Fl a
 option has no effect if other options affecting the selection of processes are
diff --git a/bin/ps/ps.c b/bin/ps/ps.c
index 03454cb2b6e..db339a76598 100644
--- a/bin/ps/ps.c
+++ b/bin/ps/ps.c
@@ -117,6 +117,7 @@ struct keyword_info {
 };
 
 struct velisthead varlist = STAILQ_HEAD_INITIALIZER(varlist);
+static struct velisthead Ovarlist = STAILQ_HEAD_INITIALIZER(Ovarlist);
 
 static int	 forceuread = DEF_UREAD; /* Do extra work to get u-area. */
 static kvm_t	*kd;
@@ -173,8 +174,6 @@ static const char dfmt[] = "pid,tt,state,time,command";
 static const char jfmt[] = "user,pid,ppid,pgid,sid,jobc,state,tt,time,command";
 static const char lfmt[] = "uid,pid,ppid,cpu,pri,nice,vsz,rss,mwchan,state,"
 			   "tt,time,command";
-static const char   o1[] = "pid";
-static const char   o2[] = "tt,state,time,command";
 static const char ufmt[] = "user,pid,%cpu,%mem,vsz,rss,tt,state,start,time,command";
 static const char vfmt[] = "pid,state,time,sl,re,pagein,vsz,rss,lim,tsiz,"
 			   "%cpu,%mem,command";
@@ -359,10 +358,7 @@ main(int argc, char *argv[])
 			nlistf = optarg;
 			break;
 		case 'O':
-			parsefmt(o1, &varlist, 1);
-			parsefmt(optarg, &varlist, 1);
-			parsefmt(o2, &varlist, 1);
-			_fmt = 1;
+			parsefmt(optarg, &Ovarlist, 1);
 			break;
 		case 'o':
 			parsefmt(optarg, &varlist, 1);
@@ -496,6 +492,26 @@ main(int argc, char *argv[])
 	if (!_fmt)
 		parsefmt(dfmt, &varlist, 0);
 
+	if (!STAILQ_EMPTY(&Ovarlist)) {
+		VARENT *const pid_entry = find_varentry("pid");
+
+		/*
+		 * We insert the keywords passed by '-O' after the process ID if
+		 * specified, else at start.
+		 */
+		if (pid_entry != NULL) {
+			struct velisthead rest;
+
+			STAILQ_SPLIT_AFTER(&varlist, pid_entry, &rest, next_ve);
+			STAILQ_CONCAT(&varlist, &Ovarlist);
+			STAILQ_CONCAT(&varlist, &rest);
+		}
+		else {
+			STAILQ_SWAP(&varlist, &Ovarlist, varent);
+			STAILQ_CONCAT(&varlist, &Ovarlist);
+		}
+	}
+
 	keywords_info = calloc(known_keywords_nb, sizeof(struct keyword_info));
 	if (keywords_info == NULL)
 		xo_errx(1, "malloc failed");