diff --git a/rcl/src/rcl/time_unix.c b/rcl/src/rcl/time_unix.c
index bc7e452..fd6cbc4 100644
--- a/rcl/src/rcl/time_unix.c
+++ b/rcl/src/rcl/time_unix.c
@@ -38,7 +38,7 @@ extern "C"
 // This id an appropriate check for clock_gettime() according to:
 //   http://man7.org/linux/man-pages/man2/clock_gettime.2.html
 # if !defined(_POSIX_TIMERS) || !_POSIX_TIMERS
-#   error no monotonic clock function available
+#  error no monotonic clock function available
 # endif  // !defined(_POSIX_TIMERS) || !_POSIX_TIMERS
 #endif  // !defined(__MACH__)