Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -240,11 +240,11 @@
 
 AC_MSG_CHECKING(whether we need -D_GNU_SOURCE)
 AC_EGREP_CPP(yes, [
 	#include <stdlib.h>
 
-	#if defined(__GLIBC__) || defined(__MINGW32__)
+	#if defined(__GLIBC__) || defined(__MINGW32__) || defined(__NEWLIB__)
 	yes
 	#endif
 ], [
 	CPPFLAGS="-D_GNU_SOURCE $CPPFLAGS"
 	AC_MSG_RESULT(yes)