diff --git a/tests/zfs-tests/tests/functional/rsend/send-c_volume.ksh b/tests/zfs-tests/tests/functional/rsend/send-c_volume.ksh
index 988ed91b9918..1bf234823459 100755
--- a/tests/zfs-tests/tests/functional/rsend/send-c_volume.ksh
+++ b/tests/zfs-tests/tests/functional/rsend/send-c_volume.ksh
@@ -1,78 +1,83 @@
 #!/bin/ksh -p
 
 #
 # This file and its contents are supplied under the terms of the
 # Common Development and Distribution License ("CDDL"), version 1.0.
 # You may only use this file in accordance with the terms of version
 # 1.0 of the CDDL.
 #
 # A full copy of the text of the CDDL should have accompanied this
 # source.  A copy of the CDDL is also available via the Internet at
 # http://www.illumos.org/license/CDDL.
 #
 
 #
 # Copyright (c) 2015 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/tests/functional/rsend/rsend.kshlib
 
 #
 # Description:
 # Verify that compressed send correctly handles volumes
 #
 # Strategy:
 # 1. Write compressible data into a volume, take a snap
 # 2. Verify the compressed stream is the correct size, and has the correct data
 # 3. Repeat step 2 for an incremental compressed stream
 #
 
 function cleanup
 {
+	rm $BACKDIR/copy
 	log_must_busy zfs destroy -r $vol
 	cleanup_pool $POOL2
 }
 
 verify_runnable "both"
 
 log_assert "Verify compressed send works with volumes"
 log_onexit cleanup
 
 typeset vol="$POOL/newvol"
 typeset vol2="$POOL2/newvol"
 typeset voldev="$ZVOL_DEVDIR/$POOL/newvol"
 typeset voldev2="$ZVOL_DEVDIR/$POOL2/newvol"
 typeset data1=$BACKDIR/file.0
 typeset data2=$BACKDIR/file.1
 typeset megs=8
 
 log_must zfs create -V 256m -o compress=lz4 $vol
 
 write_compressible $BACKDIR ${megs}m 2
 md5_1=$(md5digest $data1)
 md5_2=$(md5digest $data2)
 
 log_must dd if=$data1 of=$voldev bs=1024k
 log_must zfs snapshot $vol@snap
 
 log_must eval "zfs send -c $vol@snap >$BACKDIR/full"
 log_must eval "zfs recv -d $POOL2 <$BACKDIR/full"
 
 verify_stream_size $BACKDIR/full $vol
 verify_stream_size $BACKDIR/full $vol2
-md5=$(dd if=$voldev2 bs=1024k count=$megs 2>/dev/null | md5digest)
+block_device_wait $voldev2
+log_must dd if=$voldev2 of=$BACKDIR/copy bs=1024k count=$megs
+md5=$(md5digest $BACKDIR/copy)
 [[ $md5 = $md5_1 ]] || log_fail "md5 mismatch: $md5 != $md5_1"
 
 # Repeat, for an incremental send
 log_must dd seek=$megs if=$data2 of=$voldev bs=1024k
 log_must zfs snapshot $vol@snap2
 
 log_must eval "zfs send -c -i snap $vol@snap2 >$BACKDIR/inc"
 log_must eval "zfs recv -d $POOL2 <$BACKDIR/inc"
 
 verify_stream_size $BACKDIR/inc $vol 90 $vol@snap
 verify_stream_size $BACKDIR/inc $vol2 90 $vol2@snap
-md5=$(dd skip=$megs if=$voldev2 bs=1024k count=$megs 2>/dev/null | md5digest)
+block_device_wait $voldev2
+log_must dd skip=$megs if=$voldev2 of=$BACKDIR/copy bs=1024k count=$megs
+md5=$(md5digest $BACKDIR/copy)
 [[ $md5 = $md5_2 ]] || log_fail "md5 mismatch: $md5 != $md5_2"
 
 log_pass "Verify compressed send works with volumes"