diff --git a/tests/sys/geom/class/mirror/10_test.sh b/tests/sys/geom/class/mirror/10_test.sh
index c8187189d60dde..9247abddd82653 100644
--- a/tests/sys/geom/class/mirror/10_test.sh
+++ b/tests/sys/geom/class/mirror/10_test.sh
@@ -30,7 +30,7 @@ tmp2=$(mktemp $base.XXXXXX)
 
 EIO=5
 # gmirror should retry a failed read from the other mirror.
-sysctl ${regreadfp}="1*return(${EIO})"
+sysctl ${regreadfp}="1*return(${EIO})[pid $(gmirror_worker_pid)]"
 dd if=/dev/mirror/$name of=$tmp1 iseek=256 bs=$ddbs count=1 >/dev/null 2>&1
 dd if=/dev/$us1 of=$tmp2 iseek=256 bs=$ddbs count=1 >/dev/null 2>&1
 sysctl ${regreadfp}='off'
diff --git a/tests/sys/geom/class/mirror/11_test.sh b/tests/sys/geom/class/mirror/11_test.sh
index 284aa19c72fa4a..8ae65a1f5a04fe 100644
--- a/tests/sys/geom/class/mirror/11_test.sh
+++ b/tests/sys/geom/class/mirror/11_test.sh
@@ -31,7 +31,7 @@ tmp2=$(mktemp $base.XXXXXX)
 ENXIO=6
 # gmirror has special handling for ENXIO. It does not mark the failed component
 # as broken, allowing it to rejoin the mirror automatically when it appears.
-sysctl ${regreadfp}="1*return(${ENXIO})"
+sysctl ${regreadfp}="1*return(${ENXIO})[pid $(gmirror_worker_pid)]"
 dd if=/dev/mirror/$name of=$tmp1 iseek=512 bs=$ddbs count=1 >/dev/null 2>&1
 dd if=/dev/$us1 of=$tmp2 iseek=512 bs=$ddbs count=1 >/dev/null 2>&1
 sysctl ${regreadfp}='off'
diff --git a/tests/sys/geom/class/mirror/12_test.sh b/tests/sys/geom/class/mirror/12_test.sh
index 07d69b696adf6b..46a79efe7e05bb 100644
--- a/tests/sys/geom/class/mirror/12_test.sh
+++ b/tests/sys/geom/class/mirror/12_test.sh
@@ -29,7 +29,7 @@ dd if=/dev/random of=$tmp1 bs=$ddbs count=1 >/dev/null 2>&1
 
 EIO=5
 # gmirror should kick one of the mirrors out after hitting EIO.
-sysctl ${regwritefp}="1*return(${EIO})"
+sysctl ${regwritefp}="1*return(${EIO})[pid $(gmirror_worker_pid)]"
 dd if=$tmp1 of=/dev/mirror/$name bs=$ddbs count=1 >/dev/null 2>&1
 dd if=/dev/mirror/$name of=$tmp2 bs=$ddbs count=1 >/dev/null 2>&1
 sysctl ${regwritefp}='off'
diff --git a/tests/sys/geom/class/mirror/13_test.sh b/tests/sys/geom/class/mirror/13_test.sh
index 4a66d65321a314..4b0fc6cf7825f8 100644
--- a/tests/sys/geom/class/mirror/13_test.sh
+++ b/tests/sys/geom/class/mirror/13_test.sh
@@ -31,7 +31,7 @@ dd if=/dev/random of=$tmp1 bs=$ddbs count=1 >/dev/null 2>&1
 ENXIO=6
 # gmirror has special handling for ENXIO. It does not mark the failed component
 # as broken, allowing it to rejoin the mirror automatically when it appears.
-sysctl ${regwritefp}="1*return(${ENXIO})"
+sysctl ${regwritefp}="1*return(${ENXIO})[pid $(gmirror_worker_pid)]"
 dd if=$tmp1 of=/dev/mirror/$name bs=$ddbs count=1 >/dev/null 2>&1
 dd if=/dev/mirror/$name of=$tmp2 bs=$ddbs count=1 >/dev/null 2>&1
 sysctl ${regwritefp}='off'
diff --git a/tests/sys/geom/class/mirror/9_test.sh b/tests/sys/geom/class/mirror/9_test.sh
index c7af15ba8ed238..0c29cefd4344b6 100644
--- a/tests/sys/geom/class/mirror/9_test.sh
+++ b/tests/sys/geom/class/mirror/9_test.sh
@@ -26,7 +26,7 @@ devwait
 # Break one of the mirrors by forcing a single metadata write error.
 # When dd closes the mirror provider, gmirror will attempt to mark the mirrors
 # clean, and will kick one of the mirrors out upon hitting the error.
-sysctl debug.fail_point.g_mirror_metadata_write='1*return(5)' || exit 1
+sysctl debug.fail_point.g_mirror_metadata_write="1*return(5)[pid $(gmirror_worker_pid)]" || exit 1
 dd if=/dev/random of=/dev/mirror/$name bs=$ddbs count=1 >/dev/null 2>&1
 sysctl debug.fail_point.g_mirror_metadata_write='off' || exit 1
 
diff --git a/tests/sys/geom/class/mirror/conf.sh b/tests/sys/geom/class/mirror/conf.sh
index cee2b10e9ff6af..f50ff5f6b63625 100644
--- a/tests/sys/geom/class/mirror/conf.sh
+++ b/tests/sys/geom/class/mirror/conf.sh
@@ -12,6 +12,11 @@ gmirror_test_cleanup()
 }
 trap gmirror_test_cleanup ABRT EXIT INT TERM
 
+gmirror_worker_pid()
+{
+	pgrep -S -n "g_mirror mirror\..*"
+}
+
 syncwait()
 {
 	while $(gmirror status -s $name | grep -q SYNCHRONIZING); do
diff --git a/tests/sys/geom/class/mirror/sync_error.sh b/tests/sys/geom/class/mirror/sync_error.sh
index b5f138aaf8a054..7c736b955a68bf 100644
--- a/tests/sys/geom/class/mirror/sync_error.sh
+++ b/tests/sys/geom/class/mirror/sync_error.sh
@@ -28,7 +28,7 @@ sync_read_error_2_disks_body()
 	atf_check gmirror label $name $md1
 	devwait
 
-	atf_check -s ignore -e empty -o not-empty sysctl ${REG_READ_FP}='1*return(5)'
+	atf_check -s ignore -e empty -o not-empty sysctl ${REG_READ_FP}="1*return(5)[pid $(gmirror_worker_pid)]"
 
 	# If a read error occurs while synchronizing and the mirror contains
 	# a single active disk, gmirror has no choice but to fail the
@@ -75,7 +75,7 @@ sync_read_error_3_disks_body()
 	atf_check gmirror insert $name $md2
 	syncwait
 
-	atf_check -s exit:0 -e empty -o not-empty sysctl ${REG_READ_FP}='1*return(5)'
+	atf_check -s exit:0 -e empty -o not-empty sysctl ${REG_READ_FP}="1*return(5)[pid $(gmirror_worker_pid)]"
 
 	# If a read error occurs while synchronizing a new disk, and we have
 	# multiple active disks, we retry the read after an error. The disk