diff --git a/doc/release_new_version b/doc/release_new_version
index f2e34963..bc68a656 100644
--- a/doc/release_new_version
+++ b/doc/release_new_version
@@ -190,7 +190,7 @@ from:tange@gnu.org
 to:parallel@gnu.org, bug-parallel@gnu.org
 stable-bcc: Jesse Alama <jessealama@fastmail.fm>
 
-Subject: GNU Parallel 20201222 ('Maradona') released <<[stable]>>
+Subject: GNU Parallel 20201222 ('Maradona/Yeager') released <<[stable]>>
 
 GNU Parallel 20201222 ('') <<[stable]>> has been released. It is available for download at: http://ftpmirror.gnu.org/parallel/
 
diff --git a/src/parallel b/src/parallel
index c4697a8f..1019fb4c 100755
--- a/src/parallel
+++ b/src/parallel
@@ -860,14 +860,15 @@ sub column_perlexpr($$$) {
 sub group_by_loop($$) {
     # Generate perl code for group-by loop
     # Insert a $recsep when the column value changes
-    # The column value can be computed with $perexpr
+    # The column value can be computed with $perlexpr
     my($fh,$recsep) = @_;
     my $groupby = $opt::groupby;
     if($groupby =~ /^[a-z_][a-z_0-9]*(\s|$)/i) {
 	# Group by column name
 	# (Yes, this will also wrongly match a perlexpr like: chop)
 	my($read,$char,@line);
-	# A full line, but nothing more (the rest must be read by the child)
+	# Read a full line, but nothing more
+	# (the rest must be read by the child)
 	# $Global::header used to prepend block to each job
         do {
 	    $read = sysread($fh,$char,1);
@@ -918,12 +919,19 @@ sub group_by_stdin_filter() {
 	my $sep = $opt::colsep;
 	$sep =~ s/\t/\\t/g;
 	$sep =~ s/\"/\\"/g;
+	# man perlrun: -Fpattern [...] You can't use literal whitespace
+	$sep =~ s/ /\\040{1}/g;
 	push @filter, "-F$sep";
     }
     push @filter, "-pe";
     push @filter, group_by_loop(*STDIN,$opt::recstart);
     ::debug("init", "@filter\n");
     open(STDIN, '-|', @filter) || die ("Cannot start @filter");
+    if(which("mbuffer")) {
+	# You get a speed up of 30% by going through mbuffer
+	open(STDIN, '-|', "mbuffer", "-q","-m6M","-b5") ||
+	    die ("Cannot start mbuffer");
+    }
 }
 
 sub spreadstdin() {
@@ -2164,7 +2172,7 @@ sub check_invalid_option_combinations() {
 
 sub init_globals() {
     # Defaults:
-    $Global::version = 20201122;
+    $Global::version = 20201207;
     $Global::progname = 'parallel';
     $::name = "GNU Parallel";
     $Global::infinity = 2**31;
diff --git a/testsuite/tests-to-run/parallel-local-0.3s.sh b/testsuite/tests-to-run/parallel-local-0.3s.sh
index 04453530..fdc0b364 100644
--- a/testsuite/tests-to-run/parallel-local-0.3s.sh
+++ b/testsuite/tests-to-run/parallel-local-0.3s.sh
@@ -860,6 +860,19 @@ par_PARALLEL_HOME_with_+() {
     rm -rf "$tmp"
 }
 
+par_group-by_colsep_space() {
+    echo '### --colsep " " should work like ","'
+    input() {
+	sep="$1"
+	printf "a\t${sep}b\n"
+	printf "a${sep}${sep}b\n"
+	printf "b${sep}${sep}a\n"
+	printf "b${sep}a${sep}b\n"
+    }
+    input ',' | parallel --pipe --group-by 2 --colsep ',' -kN1 wc
+    input ' ' | parallel --pipe --group-by 2 --colsep ' ' -kN1 wc
+}
+
 export -f $(compgen -A function | grep par_)
 compgen -A function | grep par_ | LC_ALL=C sort |
     parallel --timeout 1000% -j6 --tag -k --joblog /tmp/jl-`basename $0` '{} 2>&1' |
diff --git a/testsuite/wanted-results/parallel-local-0.3s b/testsuite/wanted-results/parallel-local-0.3s
index e535c776..6f90d375 100644
--- a/testsuite/wanted-results/parallel-local-0.3s
+++ b/testsuite/wanted-results/parallel-local-0.3s
@@ -154,6 +154,13 @@ par_file_ending_in_newline	gzip '/tmp/parallel_f2
 par_file_ending_in_newline	'
 par_fish	### https://github.com/fish-shell/fish-shell/issues/5582
 par_fish	OK
+par_group-by_colsep_space	### --colsep " " should work like ","
+par_group-by_colsep_space	      1       2       5
+par_group-by_colsep_space	      2       2      10
+par_group-by_colsep_space	      1       1       6
+par_group-by_colsep_space	      1       2       5
+par_group-by_colsep_space	      2       4      10
+par_group-by_colsep_space	      1       3       6
 par_halt_on_error_division_by_zero	### --halt-on-error soon,fail=100% with no input should not give division by zero
 par_halt_on_error_division_by_zero	0
 par_halt_one_job	# Halt soon if there is a single job