diff --git a/hw/xfree86/common/Makefile.am b/hw/xfree86/common/Makefile.am
index 745278b9a..87913e8fa 100644
--- a/hw/xfree86/common/Makefile.am
+++ b/hw/xfree86/common/Makefile.am
@@ -19,7 +19,7 @@ BUSSOURCES = xf86isaBus.c xf86pciBus.c xf86fbBus.c xf86noBus.c $(SBUS_SOURCES)
 MODEDEFSOURCES = $(srcdir)/vesamodes $(srcdir)/extramodes
 
 xf86DefModeSet.c: $(srcdir)/modeline2c.awk $(MODEDEFSOURCES)
-	cat $(MODEDEFSOURCES) | $(AWK) -f $(srcdir)/modeline2c.awk > $@
+	cat $(MODEDEFSOURCES) | LC_ALL=C $(AWK) -f $(srcdir)/modeline2c.awk > $@
 	echo >> $@
 
 BUILT_SOURCES = xf86DefModeSet.c