diff -r f412e9f093d4 configure
--- a/configure	Wed Jan 25 00:47:06 2017 +0000
+++ b/configure	Sun Jan 29 19:32:47 2017 +0100
@@ -13507,7 +13507,10 @@
 	  -D*=* ) val=`echo '' $word | sed -e 's:^.*=::'` ;;
 	  *     ) val=1 ;;
 	esac
-	if grep "^#define $sym " confdefs.h >/dev/null; then :; else
+	if grep "^#define $sym " confdefs.h >/dev/null          || \
+           test "$have_glibc" = "yes" -a "$sym" = "_BSD_SOURCE" || \
+           test "$have_glibc" = "yes" -a "$sym" = "_SVID_SOURCE";
+        then :; else
 	  if test "$val" = "1"
 	    then cat >>confdefs.h <<_ACEOF
 #define $sym 1
diff -r f412e9f093d4 configure.ac
--- a/configure.ac	Wed Jan 25 00:47:06 2017 +0000
+++ b/configure.ac	Sun Jan 29 19:32:47 2017 +0100
@@ -3136,7 +3136,12 @@
 	  *     ) val=1 ;;
 	esac
 dnl Avoid re-AC_DEFINE-ing xmkmf symbols we've already defined above.
-	if grep "^#define $sym " confdefs.h >/dev/null; then :; else
+dnl Also, glibc doesn't like two of the traditional POSIX macros that xmkmf
+dnl likes us to define; ignore them if appropriate.
+	if grep "^#define $sym " confdefs.h >/dev/null          || \
+           test "$have_glibc" = "yes" -a "$sym" = "_BSD_SOURCE" || \
+           test "$have_glibc" = "yes" -a "$sym" = "_SVID_SOURCE";
+        then :; else
 	  if test "$val" = "1"
 	    then AC_DEFINE_UNQUOTED($sym)
 	    else AC_DEFINE_UNQUOTED($sym,$val)