diff --git a/qemu-img.c b/qemu-img.c
index ec0e2fabe5..7c4fc60312 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3767,6 +3767,9 @@ static int img_rebase(int argc, char **argv)
     if (ret == -ENOSPC) {
         error_report("Could not change the backing file to '%s': No "
                      "space left in the file header", out_baseimg);
+    } else if (ret == -EINVAL && out_baseimg && !out_basefmt) {
+        error_report("Could not change the backing file to '%s': backing "
+                     "format must be specified", out_baseimg);
     } else if (ret < 0) {
         error_report("Could not change the backing file to '%s': %s",
             out_baseimg, strerror(-ret));
diff --git a/tests/qemu-iotests/114.out b/tests/qemu-iotests/114.out
index 6d638da266..f51dd9d20a 100644
--- a/tests/qemu-iotests/114.out
+++ b/tests/qemu-iotests/114.out
@@ -14,7 +14,7 @@ qemu-io: can't open device TEST_DIR/t.qcow2: Could not open backing file: Unknow
 no file open, try 'help open'
 read 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-qemu-img: Could not change the backing file to 'TEST_DIR/t.qcow2.base': Invalid argument
+qemu-img: Could not change the backing file to 'TEST_DIR/t.qcow2.base': backing format must be specified
 read 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 *** done