diff --git a/tests/qemu-iotests/122 b/tests/qemu-iotests/122
index 45b359c2ba..6cf4fcb866 100755
--- a/tests/qemu-iotests/122
+++ b/tests/qemu-iotests/122
@@ -130,6 +130,53 @@ $QEMU_IO -c "read -P 0    1024k 1022k" "$TEST_IMG" 2>&1 | _filter_qemu_io | _fil
 
 
 echo
+echo "=== Corrupted size field in compressed cluster descriptor ==="
+echo
+# Create an empty image and fill half of it with compressed data.
+# The L2 entries of the two compressed clusters are located at
+# 0x800000 and 0x800008, their original values are 0x4008000000a00000
+# and 0x4008000000a00802 (5 sectors for compressed data each).
+_make_test_img 8M -o cluster_size=2M
+$QEMU_IO -c "write -c -P 0x11 0 2M" -c "write -c -P 0x11 2M 2M" "$TEST_IMG" \
+         2>&1 | _filter_qemu_io | _filter_testdir
+
+# Reduce size of compressed data to 4 sectors: this corrupts the image.
+poke_file "$TEST_IMG" $((0x800000)) "\x40\x06"
+$QEMU_IO -c "read  -P 0x11 0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
+
+# 'qemu-img check' however doesn't see anything wrong because it
+# doesn't try to decompress the data and the refcounts are consistent.
+# TODO: update qemu-img so this can be detected.
+_check_test_img
+
+# Increase size of compressed data to the maximum (8192 sectors).
+# This makes QEMU read more data (8192 sectors instead of 5, host
+# addresses [0xa00000, 0xdfffff]), but the decompression algorithm
+# stops once we have enough to restore the uncompressed cluster, so
+# the rest of the data is ignored.
+poke_file "$TEST_IMG" $((0x800000)) "\x7f\xfe"
+# Do it also for the second compressed cluster (L2 entry at 0x800008).
+# In this case the compressed data would span 3 host clusters
+# (host addresses: [0xa00802, 0xe00801])
+poke_file "$TEST_IMG" $((0x800008)) "\x7f\xfe"
+
+# Here the image is too small so we're asking QEMU to read beyond the
+# end of the image.
+$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
+# But if we grow the image we won't be reading beyond its end anymore.
+$QEMU_IO -c "write -P 0x22 4M 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
+$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
+
+# The refcount data is however wrong because due to the increased size
+# of the compressed data it now reaches the following host clusters.
+# This can be repaired by qemu-img check by increasing the refcount of
+# those clusters.
+# TODO: update qemu-img to correct the compressed cluster size instead.
+_check_test_img -r all
+$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
+$QEMU_IO -c "read  -P 0x22 4M 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
+
+echo
 echo "=== Full allocation with -S 0 ==="
 echo
 
diff --git a/tests/qemu-iotests/122.out b/tests/qemu-iotests/122.out
index 47d8656db8..a6b7fe007e 100644
--- a/tests/qemu-iotests/122.out
+++ b/tests/qemu-iotests/122.out
@@ -99,6 +99,39 @@ read 1024/1024 bytes at offset 1047552
 read 1046528/1046528 bytes at offset 1048576
 1022 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
+=== Corrupted size field in compressed cluster descriptor ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=8388608
+wrote 2097152/2097152 bytes at offset 0
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 2097152
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read failed: Input/output error
+No errors were found on the image.
+read 4194304/4194304 bytes at offset 0
+4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 4194304/4194304 bytes at offset 4194304
+4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 4194304/4194304 bytes at offset 0
+4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+ERROR cluster 6 refcount=1 reference=3
+ERROR cluster 7 refcount=1 reference=2
+Repairing cluster 6 refcount=1 reference=3
+Repairing cluster 7 refcount=1 reference=2
+Repairing OFLAG_COPIED data cluster: l2_entry=8000000000c00000 refcount=3
+Repairing OFLAG_COPIED data cluster: l2_entry=8000000000e00000 refcount=2
+The following inconsistencies were found and repaired:
+
+    0 leaked clusters
+    4 corruptions
+
+Double checking the fixed image now...
+No errors were found on the image.
+read 4194304/4194304 bytes at offset 0
+4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 4194304/4194304 bytes at offset 4194304
+4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
 === Full allocation with -S 0 ===
 
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
