diff --git a/test/compress/compress.sh b/test/compress/compress.sh
index 4ac815583..48889c5a2 100755
--- a/test/compress/compress.sh
+++ b/test/compress/compress.sh
@@ -8,6 +8,9 @@ plugindir=$rootdir/examples/bdev/fio_plugin
 source "$rootdir/scripts/common.sh"
 source "$rootdir/test/common/autotest_common.sh"
 source "$rootdir/test/nvmf/common.sh"
+
+# Declare rpc_py here, because its default value points to rpc_cmd function,
+# which does not tolerate piping arguments into it.
 rpc_py="$rootdir/scripts/rpc.py"
 
 function error_cleanup() {
diff --git a/test/iscsi_tgt/ext4test/ext4test.sh b/test/iscsi_tgt/ext4test/ext4test.sh
index 4fd9648c6..6c3847409 100755
--- a/test/iscsi_tgt/ext4test/ext4test.sh
+++ b/test/iscsi_tgt/ext4test/ext4test.sh
@@ -7,6 +7,9 @@ source $rootdir/test/iscsi_tgt/common.sh
 
 iscsitestinit
 
+# Declare rpc_py here, because its default value points to rpc_cmd function,
+# which does not tolerate piping arguments into it.
+rpc_py="$rootdir/scripts/rpc.py"
 node_base="iqn.2013-06.com.intel.ch.spdk"
 
 timing_enter start_iscsi_tgt
diff --git a/test/iscsi_tgt/multiconnection/multiconnection.sh b/test/iscsi_tgt/multiconnection/multiconnection.sh
index 35aded32a..78e3fcd3e 100755
--- a/test/iscsi_tgt/multiconnection/multiconnection.sh
+++ b/test/iscsi_tgt/multiconnection/multiconnection.sh
@@ -7,6 +7,9 @@ source $rootdir/test/iscsi_tgt/common.sh
 
 iscsitestinit
 
+# Declare rpc_py here, because its default value points to rpc_cmd function,
+# which does not tolerate piping arguments into it.
+rpc_py="$rootdir/scripts/rpc.py"
 fio_py="$rootdir/scripts/fio-wrapper"
 
 CONNECTION_NUMBER=30