diff --git a/src/Makefile.am b/src/Makefile.am
index f8237144a3..57e1d4d95b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -32,7 +32,6 @@ AM_CPPFLAGS =	-I$(top_srcdir) \
 AM_CFLAGS =	$(LIBXML_CFLAGS) \
 		$(GLIB_CFLAGS) \
 		$(WARN_CFLAGS) \
-		$(LOCK_CHECKING_CFLAGS) \
 		$(WIN32_EXTRA_CFLAGS) \
 		$(COVERAGE_CFLAGS) \
 		$(NULL)