diff --git a/powerline/lib/shell.py b/powerline/lib/shell.py
index ef6cec41..121cea58 100644
--- a/powerline/lib/shell.py
+++ b/powerline/lib/shell.py
@@ -7,7 +7,7 @@ def run_cmd(pl, cmd, stdin=None):
 	try:
 		p = Popen(cmd, stdout=PIPE, stdin=PIPE)
 	except OSError as e:
-		pl.exception('Could not execute command ({0}): {1}'.format(e, cmd))
+		pl.exception('Could not execute command ({0}): {1}', e, cmd)
 		return None
 	else:
 		stdout, err = p.communicate(stdin)