diff --git a/configure.ac b/configure.ac
index f94d29c6d4..84c36ae4e0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -278,7 +278,7 @@ AS_IF([test -z "$with_session_tracking"], with_session_tracking=consolekit)
 AS_IF([test "$with_session_tracking" = "ck"], with_session_tracking=consolekit)
 AS_IF([test "$with_session_tracking" = "none"], with_session_tracking=no)
 # check value
-AS_IF([! echo "$with_session_tracking" | grep -q -E "^(systemd|consolekit|no)$"],
+AS_IF([! (echo "$with_session_tracking" | grep -q -E "^(systemd|consolekit|no)$")],
 	AC_MSG_ERROR([--with-session-tracking must be systemd/consolekit/no, not $with_session_tracking]))
 # add conditionals and subtitutions
 AM_CONDITIONAL(SESSION_TRACKING_CK, test "$with_session_tracking" = "consolekit")