Makefile.PL                   | 6 ++++--
 lib/PublicInbox/V2Writable.pm | 7 +++----

diff --git a/Makefile.PL b/Makefile.PL
index 8d90ad46cf64c0753b5ad9823b1553860231d30b..831649f967f27609e79e46606707e02a10ae8ff0 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -156,12 +156,14 @@ 	MAN3PODS => \%man3,
 );
 
 sub MY::postamble {
-  <<EOF;
+	my $N = (`{ getconf _NPROCESSORS_ONLN || nproc; } 2>/dev/null` || 1);
+	$N += 1; # account for sleeps in some tests (and makes an IV)
+	<<EOF;
 PROVE = prove
 # support using eatmydata to speed up tests (apt-get install eatmydata):
 # https://www.flamingspork.com/projects/libeatmydata/
 EATMYDATA =
-N = \$\$(( \$\$(nproc 2>/dev/null || gnproc 2>/dev/null || echo 2) + 1 ))
+N = $N
 -include config.mak
 $VARS
 -include Documentation/include.mk
diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index f7a318e5b7f39f96342f65c6821a16c3edfa4b34..dfcb489723d29a6faf0283efb133585e4a5949e6 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -35,13 +35,12 @@ # to increase Xapian shards
 our $NPROC_MAX_DEFAULT = 4;
 
 sub detect_nproc () {
-	for my $nproc (qw(nproc gnproc)) { # GNU coreutils nproc
-		`$nproc 2>/dev/null` =~ /^(\d+)$/ and return $1;
-	}
-
 	# getconf(1) is POSIX, but *NPROCESSORS* vars are not
 	for (qw(_NPROCESSORS_ONLN NPROCESSORS_ONLN)) {
 		`getconf $_ 2>/dev/null` =~ /^(\d+)$/ and return $1;
+	}
+	for my $nproc (qw(nproc gnproc)) { # GNU coreutils nproc
+		`$nproc 2>/dev/null` =~ /^(\d+)$/ and return $1;
 	}
 
 	# should we bother with `sysctl hw.ncpu`?  Those only give