diff --git a/Makefile.in b/Makefile.in
index e172daab6..a2a4b20c6 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -49,7 +49,7 @@ prefix = @prefix@
 optbindirs = @optbindirs@
 PACKAGE_TARNAME = @PACKAGE_TARNAME@
 
-MACROS=-DLOCALEDIR=\"$(localedir)\" -DPREFIX=L\"$(prefix)\" -DDATADIR=L\"$(datadir)\" -DSYSCONFDIR=L\"$(sysconfdir)\"
+MACROS=-DLOCALEDIR=\"$(localedir)\" -DPREFIX=L\"$(prefix)\" -DDATADIR=L\"$(datadir)\" -DSYSCONFDIR=L\"$(sysconfdir)\" -D_POSIX_C_SOURCE=200112L
 CFLAGS=@CFLAGS@ $(MACROS)
 CPPFLAGS=@CPPFLAGS@
 LDFLAGS= @LIBS@ @LDFLAGS@