diff --git a/test/py/tests/test_vboot.py b/test/py/tests/test_vboot.py
index d7ab439..021892b 100644
--- a/test/py/tests/test_vboot.py
+++ b/test/py/tests/test_vboot.py
@@ -71,7 +71,7 @@
                 ['sb load hostfs - 100 %stest.fit' % tmpdir,
                 'fdt addr 100',
                 'bootm 100'])
-        assert(expect_string in output)
+        assert(expect_string in ''.join(output))
 
     def make_fit(its):
         """Make a new FIT from the .its source file.
diff --git a/test/py/u_boot_console_base.py b/test/py/u_boot_console_base.py
index b855b10..ee9b928 100644
--- a/test/py/u_boot_console_base.py
+++ b/test/py/u_boot_console_base.py
@@ -225,11 +225,12 @@
         Args:
             cmd: List of commands (each a string).
         Returns:
-            Combined output of all commands, as a string.
+            A list of output strings from each command, one element for each
+            command.
         """
-        output = ''
+        output = []
         for cmd in cmds:
-            output += self.run_command(cmd)
+            output.append(self.run_command(cmd))
         return output
 
     def ctrlc(self):